1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see http://lists.denx.de/pipermail/u-boot and
55 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58 Where to get source code:
59 =========================
61 The U-Boot source code is maintained in the Git repository at
62 git://www.denx.de/git/u-boot.git ; you can browse it online at
63 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
65 The "snapshot" links on this page allow you to download tarballs of
66 any version you might be interested in. Official releases are also
67 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
70 Pre-built (and tested) images are available from
71 ftp://ftp.denx.de/pub/u-boot/images/
77 - start from 8xxrom sources
78 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
80 - make it easier to add custom boards
81 - make it possible to add other [PowerPC] CPUs
82 - extend functions, especially:
83 * Provide extended interface to Linux boot loader
86 * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87 - create ARMBoot project (http://sourceforge.net/projects/armboot)
88 - add other CPU families (starting with ARM)
89 - create U-Boot project (http://sourceforge.net/projects/u-boot)
90 - current project page: see http://www.denx.de/wiki/U-Boot
96 The "official" name of this project is "Das U-Boot". The spelling
97 "U-Boot" shall be used in all written text (documentation, comments
98 in source files etc.). Example:
100 This is the README file for the U-Boot project.
102 File names etc. shall be based on the string "u-boot". Examples:
104 include/asm-ppc/u-boot.h
106 #include <asm/u-boot.h>
108 Variable names, preprocessor constants etc. shall be either based on
109 the string "u_boot" or on "U_BOOT". Example:
111 U_BOOT_VERSION u_boot_logo
112 IH_OS_U_BOOT u_boot_hush_start
118 Starting with the release in October 2008, the names of the releases
119 were changed from numerical release numbers without deeper meaning
120 into a time stamp based numbering. Regular releases are identified by
121 names consisting of the calendar year and month of the release date.
122 Additional fields (if present) indicate release candidates or bug fix
123 releases in "stable" maintenance trees.
126 U-Boot v2009.11 - Release November 2009
127 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
128 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
134 /arch Architecture specific files
135 /arc Files generic to ARC architecture
136 /arm Files generic to ARM architecture
137 /m68k Files generic to m68k architecture
138 /microblaze Files generic to microblaze architecture
139 /mips Files generic to MIPS architecture
140 /nds32 Files generic to NDS32 architecture
141 /nios2 Files generic to Altera NIOS2 architecture
142 /openrisc Files generic to OpenRISC architecture
143 /powerpc Files generic to PowerPC architecture
144 /riscv Files generic to RISC-V architecture
145 /sandbox Files generic to HW-independent "sandbox"
146 /sh Files generic to SH architecture
147 /x86 Files generic to x86 architecture
148 /api Machine/arch independent API for external apps
149 /board Board dependent files
150 /cmd U-Boot commands functions
151 /common Misc architecture independent functions
152 /configs Board default configuration files
153 /disk Code for disk drive partition handling
154 /doc Documentation (don't expect too much)
155 /drivers Commonly used device drivers
156 /dts Contains Makefile for building internal U-Boot fdt.
157 /examples Example code for standalone applications, etc.
158 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
159 /include Header Files
160 /lib Library routines generic to all architectures
161 /Licenses Various license files
163 /post Power On Self Test
164 /scripts Various build scripts and Makefiles
165 /test Various unit test files
166 /tools Tools to build S-Record or U-Boot images, etc.
168 Software Configuration:
169 =======================
171 Configuration is usually done using C preprocessor defines; the
172 rationale behind that is to avoid dead code whenever possible.
174 There are two classes of configuration variables:
176 * Configuration _OPTIONS_:
177 These are selectable by the user and have names beginning with
180 * Configuration _SETTINGS_:
181 These depend on the hardware etc. and should not be meddled with if
182 you don't know what you're doing; they have names beginning with
185 Previously, all configuration was done by hand, which involved creating
186 symbolic links and editing configuration files manually. More recently,
187 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
188 allowing you to use the "make menuconfig" command to configure your
192 Selection of Processor Architecture and Board Type:
193 ---------------------------------------------------
195 For all supported boards there are ready-to-use default
196 configurations available; just type "make <board_name>_defconfig".
198 Example: For a TQM823L module type:
201 make TQM823L_defconfig
203 Note: If you're looking for the default configuration file for a board
204 you're sure used to be there but is now missing, check the file
205 doc/README.scrapyard for a list of no longer supported boards.
210 U-Boot can be built natively to run on a Linux host using the 'sandbox'
211 board. This allows feature development which is not board- or architecture-
212 specific to be undertaken on a native platform. The sandbox is also used to
213 run some of U-Boot's tests.
215 See doc/arch/index.rst for more details.
218 Board Initialisation Flow:
219 --------------------------
221 This is the intended start-up flow for boards. This should apply for both
222 SPL and U-Boot proper (i.e. they both follow the same rules).
224 Note: "SPL" stands for "Secondary Program Loader," which is explained in
225 more detail later in this file.
227 At present, SPL mostly uses a separate code path, but the function names
228 and roles of each function are the same. Some boards or architectures
229 may not conform to this. At least most ARM boards which use
230 CONFIG_SPL_FRAMEWORK conform to this.
232 Execution typically starts with an architecture-specific (and possibly
233 CPU-specific) start.S file, such as:
235 - arch/arm/cpu/armv7/start.S
236 - arch/powerpc/cpu/mpc83xx/start.S
237 - arch/mips/cpu/start.S
239 and so on. From there, three functions are called; the purpose and
240 limitations of each of these functions are described below.
243 - purpose: essential init to permit execution to reach board_init_f()
244 - no global_data or BSS
245 - there is no stack (ARMv7 may have one but it will soon be removed)
246 - must not set up SDRAM or use console
247 - must only do the bare minimum to allow execution to continue to
249 - this is almost never needed
250 - return normally from this function
253 - purpose: set up the machine ready for running board_init_r():
254 i.e. SDRAM and serial UART
255 - global_data is available
257 - BSS is not available, so you cannot use global/static variables,
258 only stack variables and global_data
260 Non-SPL-specific notes:
261 - dram_init() is called to set up DRAM. If already done in SPL this
265 - you can override the entire board_init_f() function with your own
267 - preloader_console_init() can be called here in extremis
268 - should set up SDRAM, and anything needed to make the UART work
269 - these is no need to clear BSS, it will be done by crt0.S
270 - must return normally from this function (don't call board_init_r()
273 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
274 this point the stack and global_data are relocated to below
275 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
279 - purpose: main execution, common code
280 - global_data is available
282 - BSS is available, all static/global variables can be used
283 - execution eventually continues to main_loop()
285 Non-SPL-specific notes:
286 - U-Boot is relocated to the top of memory and is now running from
290 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
291 CONFIG_SPL_STACK_R_ADDR points into SDRAM
292 - preloader_console_init() can be called here - typically this is
293 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
294 spl_board_init() function containing this call
295 - loads U-Boot or (in falcon mode) Linux
299 Configuration Options:
300 ----------------------
302 Configuration depends on the combination of board and CPU type; all
303 such information is kept in a configuration file
304 "include/configs/<board_name>.h".
306 Example: For a TQM823L module, all configuration settings are in
307 "include/configs/TQM823L.h".
310 Many of the options are named exactly as the corresponding Linux
311 kernel configuration options. The intention is to make it easier to
312 build a config tool - later.
314 - ARM Platform Bus Type(CCI):
315 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
316 provides full cache coherency between two clusters of multi-core
317 CPUs and I/O coherency for devices and I/O masters
319 CONFIG_SYS_FSL_HAS_CCI400
321 Defined For SoC that has cache coherent interconnect
324 CONFIG_SYS_FSL_HAS_CCN504
326 Defined for SoC that has cache coherent interconnect CCN-504
328 The following options need to be configured:
330 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
332 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
337 Specifies that the core is a 64-bit PowerPC implementation (implements
338 the "64" category of the Power ISA). This is necessary for ePAPR
339 compliance, among other possible reasons.
341 CONFIG_SYS_FSL_TBCLK_DIV
343 Defines the core time base clock divider ratio compared to the
344 system clock. On most PQ3 devices this is 8, on newer QorIQ
345 devices it can be 16 or 32. The ratio varies from SoC to Soc.
347 CONFIG_SYS_FSL_PCIE_COMPAT
349 Defines the string to utilize when trying to match PCIe device
350 tree nodes for the given platform.
352 CONFIG_SYS_FSL_ERRATUM_A004510
354 Enables a workaround for erratum A004510. If set,
355 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
356 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
358 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
359 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
361 Defines one or two SoC revisions (low 8 bits of SVR)
362 for which the A004510 workaround should be applied.
364 The rest of SVR is either not relevant to the decision
365 of whether the erratum is present (e.g. p2040 versus
366 p2041) or is implied by the build target, which controls
367 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
369 See Freescale App Note 4493 for more information about
372 CONFIG_A003399_NOR_WORKAROUND
373 Enables a workaround for IFC erratum A003399. It is only
374 required during NOR boot.
376 CONFIG_A008044_WORKAROUND
377 Enables a workaround for T1040/T1042 erratum A008044. It is only
378 required during NAND boot and valid for Rev 1.0 SoC revision
380 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
382 This is the value to write into CCSR offset 0x18600
383 according to the A004510 workaround.
385 CONFIG_SYS_FSL_DSP_DDR_ADDR
386 This value denotes start offset of DDR memory which is
387 connected exclusively to the DSP cores.
389 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
390 This value denotes start offset of M2 memory
391 which is directly connected to the DSP core.
393 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
394 This value denotes start offset of M3 memory which is directly
395 connected to the DSP core.
397 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
398 This value denotes start offset of DSP CCSR space.
400 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
401 Single Source Clock is clocking mode present in some of FSL SoC's.
402 In this mode, a single differential clock is used to supply
403 clocks to the sysclock, ddrclock and usbclock.
405 CONFIG_SYS_CPC_REINIT_F
406 This CONFIG is defined when the CPC is configured as SRAM at the
407 time of U-Boot entry and is required to be re-initialized.
410 Indicates this SoC supports deep sleep feature. If deep sleep is
411 supported, core will start to execute uboot when wakes up.
413 - Generic CPU options:
414 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
416 Defines the endianess of the CPU. Implementation of those
417 values is arch specific.
420 Freescale DDR driver in use. This type of DDR controller is
421 found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
424 CONFIG_SYS_FSL_DDR_ADDR
425 Freescale DDR memory-mapped register base.
427 CONFIG_SYS_FSL_DDR_EMU
428 Specify emulator support for DDR. Some DDR features such as
429 deskew training are not available.
431 CONFIG_SYS_FSL_DDRC_GEN1
432 Freescale DDR1 controller.
434 CONFIG_SYS_FSL_DDRC_GEN2
435 Freescale DDR2 controller.
437 CONFIG_SYS_FSL_DDRC_GEN3
438 Freescale DDR3 controller.
440 CONFIG_SYS_FSL_DDRC_GEN4
441 Freescale DDR4 controller.
443 CONFIG_SYS_FSL_DDRC_ARM_GEN3
444 Freescale DDR3 controller for ARM-based SoCs.
447 Board config to use DDR1. It can be enabled for SoCs with
448 Freescale DDR1 or DDR2 controllers, depending on the board
452 Board config to use DDR2. It can be enabled for SoCs with
453 Freescale DDR2 or DDR3 controllers, depending on the board
457 Board config to use DDR3. It can be enabled for SoCs with
458 Freescale DDR3 or DDR3L controllers.
461 Board config to use DDR3L. It can be enabled for SoCs with
465 Board config to use DDR4. It can be enabled for SoCs with
468 CONFIG_SYS_FSL_IFC_BE
469 Defines the IFC controller register space as Big Endian
471 CONFIG_SYS_FSL_IFC_LE
472 Defines the IFC controller register space as Little Endian
474 CONFIG_SYS_FSL_IFC_CLK_DIV
475 Defines divider of platform clock(clock input to IFC controller).
477 CONFIG_SYS_FSL_LBC_CLK_DIV
478 Defines divider of platform clock(clock input to eLBC controller).
480 CONFIG_SYS_FSL_PBL_PBI
481 It enables addition of RCW (Power on reset configuration) in built image.
482 Please refer doc/README.pblimage for more details
484 CONFIG_SYS_FSL_PBL_RCW
485 It adds PBI(pre-boot instructions) commands in u-boot build image.
486 PBI commands can be used to configure SoC before it starts the execution.
487 Please refer doc/README.pblimage for more details
489 CONFIG_SYS_FSL_DDR_BE
490 Defines the DDR controller register space as Big Endian
492 CONFIG_SYS_FSL_DDR_LE
493 Defines the DDR controller register space as Little Endian
495 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
496 Physical address from the view of DDR controllers. It is the
497 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
498 it could be different for ARM SoCs.
500 CONFIG_SYS_FSL_DDR_INTLV_256B
501 DDR controller interleaving on 256-byte. This is a special
502 interleaving mode, handled by Dickens for Freescale layerscape
505 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
506 Number of controllers used as main memory.
508 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
509 Number of controllers used for other than main memory.
511 CONFIG_SYS_FSL_HAS_DP_DDR
512 Defines the SoC has DP-DDR used for DPAA.
514 CONFIG_SYS_FSL_SEC_BE
515 Defines the SEC controller register space as Big Endian
517 CONFIG_SYS_FSL_SEC_LE
518 Defines the SEC controller register space as Little Endian
521 CONFIG_SYS_INIT_SP_OFFSET
523 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
524 pointer. This is needed for the temporary stack before
527 CONFIG_XWAY_SWAP_BYTES
529 Enable compilation of tools/xway-swap-bytes needed for Lantiq
530 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
531 be swapped if a flash programmer is used.
534 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
536 Select high exception vectors of the ARM core, e.g., do not
537 clear the V bit of the c1 register of CP15.
540 Generic timer clock source frequency.
542 COUNTER_FREQUENCY_REAL
543 Generic timer clock source frequency if the real clock is
544 different from COUNTER_FREQUENCY, and can only be determined
548 CONFIG_TEGRA_SUPPORT_NON_SECURE
550 Support executing U-Boot in non-secure (NS) mode. Certain
551 impossible actions will be skipped if the CPU is in NS mode,
552 such as ARM architectural timer initialization.
554 - Linux Kernel Interface:
557 U-Boot stores all clock information in Hz
558 internally. For binary compatibility with older Linux
559 kernels (which expect the clocks passed in the
560 bd_info data to be in MHz) the environment variable
561 "clocks_in_mhz" can be defined so that U-Boot
562 converts clock data to MHZ before passing it to the
564 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
565 "clocks_in_mhz=1" is automatically included in the
568 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
570 When transferring memsize parameter to Linux, some versions
571 expect it to be in bytes, others in MB.
572 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
576 New kernel versions are expecting firmware settings to be
577 passed using flattened device trees (based on open firmware
581 * New libfdt-based support
582 * Adds the "fdt" command
583 * The bootm command automatically updates the fdt
585 OF_TBCLK - The timebase frequency.
586 OF_STDOUT_PATH - The path to the console device
588 boards with QUICC Engines require OF_QE to set UCC MAC
591 CONFIG_OF_BOARD_SETUP
593 Board code has addition modification that it wants to make
594 to the flat device tree before handing it off to the kernel
596 CONFIG_OF_SYSTEM_SETUP
598 Other code has addition modification that it wants to make
599 to the flat device tree before handing it off to the kernel.
600 This causes ft_system_setup() to be called before booting
605 U-Boot can detect if an IDE device is present or not.
606 If not, and this new config option is activated, U-Boot
607 removes the ATA node from the DTS before booting Linux,
608 so the Linux IDE driver does not probe the device and
609 crash. This is needed for buggy hardware (uc101) where
610 no pull down resistor is connected to the signal IDE5V_DD7.
612 CONFIG_MACH_TYPE [relevant for ARM only][mandatory]
614 This setting is mandatory for all boards that have only one
615 machine type and must be used to specify the machine type
616 number as it appears in the ARM machine registry
617 (see http://www.arm.linux.org.uk/developer/machines/).
618 Only boards that have multiple machine types supported
619 in a single configuration file and the machine type is
620 runtime discoverable, do not have to use this setting.
622 - vxWorks boot parameters:
624 bootvx constructs a valid bootline using the following
625 environments variables: bootdev, bootfile, ipaddr, netmask,
626 serverip, gatewayip, hostname, othbootargs.
627 It loads the vxWorks image pointed bootfile.
629 Note: If a "bootargs" environment is defined, it will overwride
630 the defaults discussed just above.
632 - Cache Configuration:
633 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
635 - Cache Configuration for ARM:
636 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
638 CONFIG_SYS_PL310_BASE - Physical base address of PL310
639 controller register space
644 Define this if you want support for Amba PrimeCell PL010 UARTs.
648 Define this if you want support for Amba PrimeCell PL011 UARTs.
652 If you have Amba PrimeCell PL011 UARTs, set this variable to
653 the clock speed of the UARTs.
657 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
658 define this to a list of base addresses for each (supported)
659 port. See e.g. include/configs/versatile.h
661 CONFIG_SERIAL_HW_FLOW_CONTROL
663 Define this variable to enable hw flow control in serial driver.
664 Current user of this option is drivers/serial/nsl16550.c driver
667 CONFIG_BAUDRATE - in bps
668 Select one of the baudrates listed in
669 CONFIG_SYS_BAUDRATE_TABLE, see below.
673 Only needed when CONFIG_BOOTDELAY is enabled;
674 define a command string that is automatically executed
675 when no character is read on the console interface
676 within "Boot Delay" after reset.
678 CONFIG_RAMBOOT and CONFIG_NFSBOOT
679 The value of these goes into the environment as
680 "ramboot" and "nfsboot" respectively, and can be used
681 as a convenience, when switching between booting from
684 - Serial Download Echo Mode:
686 If defined to 1, all characters received during a
687 serial download (using the "loads" command) are
688 echoed back. This might be needed by some terminal
689 emulations (like "cu"), but may as well just take
690 time on others. This setting #define's the initial
691 value of the "loads_echo" environment variable.
693 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
695 Select one of the baudrates listed in
696 CONFIG_SYS_BAUDRATE_TABLE, see below.
698 - Removal of commands
699 If no commands are needed to boot, you can disable
700 CONFIG_CMDLINE to remove them. In this case, the command line
701 will not be available, and when U-Boot wants to execute the
702 boot command (on start-up) it will call board_run_command()
703 instead. This can reduce image size significantly for very
704 simple boot procedures.
706 - Regular expression support:
708 If this variable is defined, U-Boot is linked against
709 the SLRE (Super Light Regular Expression) library,
710 which adds regex support to some commands, as for
711 example "env grep" and "setexpr".
715 If this variable is defined, U-Boot will use a device tree
716 to configure its devices, instead of relying on statically
717 compiled #defines in the board file. This option is
718 experimental and only available on a few boards. The device
719 tree is available in the global data as gd->fdt_blob.
721 U-Boot needs to get its device tree from somewhere. This can
722 be done using one of the three options below:
725 If this variable is defined, U-Boot will embed a device tree
726 binary in its image. This device tree file should be in the
727 board directory and called <soc>-<board>.dts. The binary file
728 is then picked up in board_init_f() and made available through
729 the global data structure as gd->fdt_blob.
732 If this variable is defined, U-Boot will build a device tree
733 binary. It will be called u-boot.dtb. Architecture-specific
734 code will locate it at run-time. Generally this works by:
736 cat u-boot.bin u-boot.dtb >image.bin
738 and in fact, U-Boot does this for you, creating a file called
739 u-boot-dtb.bin which is useful in the common case. You can
740 still use the individual files if you need something more
744 If this variable is defined, U-Boot will use the device tree
745 provided by the board at runtime instead of embedding one with
746 the image. Only boards defining board_fdt_blob_setup() support
747 this option (see include/fdtdec.h file).
751 If this variable is defined, it enables watchdog
752 support for the SoC. There must be support in the SoC
753 specific code for a watchdog. For the 8xx
754 CPUs, the SIU Watchdog feature is enabled in the SYPCR
755 register. When supported for a specific SoC is
756 available, then no further board specific code should
760 When using a watchdog circuitry external to the used
761 SoC, then define this variable and provide board
762 specific code for the "hw_watchdog_reset" function.
766 When CONFIG_CMD_DATE is selected, the type of the RTC
767 has to be selected, too. Define exactly one of the
770 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
771 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
772 CONFIG_RTC_MC146818 - use MC146818 RTC
773 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
774 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
775 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
776 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
777 CONFIG_RTC_DS164x - use Dallas DS164x RTC
778 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
779 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
780 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
781 CONFIG_SYS_RV3029_TCR - enable trickle charger on
784 Note that if the RTC uses I2C, then the I2C interface
785 must also be configured. See I2C Support, below.
788 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
790 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
791 chip-ngpio pairs that tell the PCA953X driver the number of
792 pins supported by a particular chip.
794 Note that if the GPIO device uses I2C, then the I2C interface
795 must also be configured. See I2C Support, below.
798 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
799 accesses and can checksum them or write a list of them out
800 to memory. See the 'iotrace' command for details. This is
801 useful for testing device drivers since it can confirm that
802 the driver behaves the same way before and after a code
803 change. Currently this is supported on sandbox and arm. To
804 add support for your architecture, add '#include <iotrace.h>'
805 to the bottom of arch/<arch>/include/asm/io.h and test.
807 Example output from the 'iotrace stats' command is below.
808 Note that if the trace buffer is exhausted, the checksum will
809 still continue to operate.
812 Start: 10000000 (buffer start address)
813 Size: 00010000 (buffer size)
814 Offset: 00000120 (current buffer offset)
815 Output: 10000120 (start + offset)
816 Count: 00000018 (number of trace records)
817 CRC32: 9526fb66 (CRC32 of all trace records)
821 When CONFIG_TIMESTAMP is selected, the timestamp
822 (date and time) of an image is printed by image
823 commands like bootm or iminfo. This option is
824 automatically enabled when you select CONFIG_CMD_DATE .
826 - Partition Labels (disklabels) Supported:
827 Zero or more of the following:
828 CONFIG_MAC_PARTITION Apple's MacOS partition table.
829 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
830 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
831 bootloader. Note 2TB partition limit; see
833 CONFIG_SCSI) you must configure support for at
834 least one non-MTD partition type as well.
837 CONFIG_IDE_RESET_ROUTINE - this is defined in several
838 board configurations files but used nowhere!
840 CONFIG_IDE_RESET - is this is defined, IDE Reset will
841 be performed by calling the function
842 ide_set_reset(int reset)
843 which has to be defined in a board specific file
848 Set this to enable ATAPI support.
853 Set this to enable support for disks larger than 137GB
854 Also look at CONFIG_SYS_64BIT_LBA.
855 Whithout these , LBA48 support uses 32bit variables and will 'only'
856 support disks up to 2.1TB.
858 CONFIG_SYS_64BIT_LBA:
859 When enabled, makes the IDE subsystem use 64bit sector addresses.
863 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
864 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
865 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
866 maximum numbers of LUNs, SCSI ID's and target
869 The environment variable 'scsidevs' is set to the number of
870 SCSI devices found during the last scan.
872 - NETWORK Support (PCI):
874 Support for Intel 8254x/8257x gigabit chips.
877 Utility code for direct access to the SPI bus on Intel 8257x.
878 This does not do anything useful unless you set at least one
879 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
881 CONFIG_E1000_SPI_GENERIC
882 Allow generic access to the SPI bus on the Intel 8257x, for
883 example with the "sspi" command.
886 Support for Intel 82557/82559/82559ER chips.
887 Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
888 write routine for first time initialisation.
891 Support for Digital 2114x chips.
892 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
893 modem chip initialisation (KS8761/QS6611).
896 Support for National dp83815 chips.
899 Support for National dp8382[01] gigabit chips.
901 - NETWORK Support (other):
903 CONFIG_DRIVER_AT91EMAC
904 Support for AT91RM9200 EMAC.
907 Define this to use reduced MII inteface
909 CONFIG_DRIVER_AT91EMAC_QUIET
910 If this defined, the driver is quiet.
911 The driver doen't show link status messages.
914 Support for the Calxeda XGMAC device
917 Support for SMSC's LAN91C96 chips.
919 CONFIG_LAN91C96_USE_32_BIT
920 Define this to enable 32 bit addressing
923 Support for SMSC's LAN91C111 chip
926 Define this to hold the physical address
927 of the device (I/O space)
929 CONFIG_SMC_USE_32_BIT
930 Define this if data bus is 32 bits
932 CONFIG_SMC_USE_IOFUNCS
933 Define this to use i/o functions instead of macros
934 (some hardware wont work with macros)
936 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
937 Define this if you have more then 3 PHYs.
940 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
942 CONFIG_FTGMAC100_EGIGA
943 Define this to use GE link update with gigabit PHY.
944 Define this if FTGMAC100 is connected to gigabit PHY.
945 If your system has 10/100 PHY only, it might not occur
946 wrong behavior. Because PHY usually return timeout or
947 useless data when polling gigabit status and gigabit
948 control registers. This behavior won't affect the
949 correctnessof 10/100 link speed update.
952 Support for Renesas on-chip Ethernet controller
954 CONFIG_SH_ETHER_USE_PORT
955 Define the number of ports to be used
957 CONFIG_SH_ETHER_PHY_ADDR
958 Define the ETH PHY's address
960 CONFIG_SH_ETHER_CACHE_WRITEBACK
961 If this option is set, the driver enables cache flush.
967 CONFIG_TPM_TIS_INFINEON
968 Support for Infineon i2c bus TPM devices. Only one device
969 per system is supported at this time.
971 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
972 Define the burst count bytes upper limit
975 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
977 CONFIG_TPM_ST33ZP24_I2C
978 Support for STMicroelectronics ST33ZP24 I2C devices.
979 Requires TPM_ST33ZP24 and I2C.
981 CONFIG_TPM_ST33ZP24_SPI
982 Support for STMicroelectronics ST33ZP24 SPI devices.
983 Requires TPM_ST33ZP24 and SPI.
986 Support for Atmel TWI TPM device. Requires I2C support.
989 Support for generic parallel port TPM devices. Only one device
990 per system is supported at this time.
992 CONFIG_TPM_TIS_BASE_ADDRESS
993 Base address where the generic TPM device is mapped
994 to. Contemporary x86 systems usually map it at
998 Define this to enable the TPM support library which provides
999 functional interfaces to some TPM commands.
1000 Requires support for a TPM device.
1002 CONFIG_TPM_AUTH_SESSIONS
1003 Define this to enable authorized functions in the TPM library.
1004 Requires CONFIG_TPM and CONFIG_SHA1.
1007 At the moment only the UHCI host controller is
1008 supported (PIP405, MIP405); define
1009 CONFIG_USB_UHCI to enable it.
1010 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1011 and define CONFIG_USB_STORAGE to enable the USB
1014 Supported are USB Keyboards and USB Floppy drives
1017 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1018 txfilltuning field in the EHCI controller on reset.
1020 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1021 HW module registers.
1024 Define the below if you wish to use the USB console.
1025 Once firmware is rebuilt from a serial console issue the
1026 command "setenv stdin usbtty; setenv stdout usbtty" and
1027 attach your USB cable. The Unix command "dmesg" should print
1028 it has found a new device. The environment variable usbtty
1029 can be set to gserial or cdc_acm to enable your device to
1030 appear to a USB host as a Linux gserial device or a
1031 Common Device Class Abstract Control Model serial device.
1032 If you select usbtty = gserial you should be able to enumerate
1034 # modprobe usbserial vendor=0xVendorID product=0xProductID
1035 else if using cdc_acm, simply setting the environment
1036 variable usbtty to be cdc_acm should suffice. The following
1037 might be defined in YourBoardName.h
1040 Define this to build a UDC device
1043 Define this to have a tty type of device available to
1044 talk to the UDC device
1047 Define this to enable the high speed support for usb
1048 device and usbtty. If this feature is enabled, a routine
1049 int is_usbd_high_speed(void)
1050 also needs to be defined by the driver to dynamically poll
1051 whether the enumeration has succeded at high speed or full
1054 CONFIG_SYS_CONSOLE_IS_IN_ENV
1055 Define this if you want stdin, stdout &/or stderr to
1058 If you have a USB-IF assigned VendorID then you may wish to
1059 define your own vendor specific values either in BoardName.h
1060 or directly in usbd_vendor_info.h. If you don't define
1061 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1062 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1063 should pretend to be a Linux device to it's target host.
1065 CONFIG_USBD_MANUFACTURER
1066 Define this string as the name of your company for
1067 - CONFIG_USBD_MANUFACTURER "my company"
1069 CONFIG_USBD_PRODUCT_NAME
1070 Define this string as the name of your product
1071 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
1073 CONFIG_USBD_VENDORID
1074 Define this as your assigned Vendor ID from the USB
1075 Implementors Forum. This *must* be a genuine Vendor ID
1076 to avoid polluting the USB namespace.
1077 - CONFIG_USBD_VENDORID 0xFFFF
1079 CONFIG_USBD_PRODUCTID
1080 Define this as the unique Product ID
1082 - CONFIG_USBD_PRODUCTID 0xFFFF
1084 - ULPI Layer Support:
1085 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1086 the generic ULPI layer. The generic layer accesses the ULPI PHY
1087 via the platform viewport, so you need both the genric layer and
1088 the viewport enabled. Currently only Chipidea/ARC based
1089 viewport is supported.
1090 To enable the ULPI layer support, define CONFIG_USB_ULPI and
1091 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1092 If your ULPI phy needs a different reference clock than the
1093 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1094 the appropriate value in Hz.
1097 The MMC controller on the Intel PXA is supported. To
1098 enable this define CONFIG_MMC. The MMC can be
1099 accessed from the boot prompt by mapping the device
1100 to physical memory similar to flash. Command line is
1101 enabled with CONFIG_CMD_MMC. The MMC driver also works with
1102 the FAT fs. This is enabled with CONFIG_CMD_FAT.
1105 Support for Renesas on-chip MMCIF controller
1107 CONFIG_SH_MMCIF_ADDR
1108 Define the base address of MMCIF registers
1111 Define the clock frequency for MMCIF
1113 - USB Device Firmware Update (DFU) class support:
1115 This enables the USB portion of the DFU USB class
1118 This enables support for exposing NAND devices via DFU.
1121 This enables support for exposing RAM via DFU.
1122 Note: DFU spec refer to non-volatile memory usage, but
1123 allow usages beyond the scope of spec - here RAM usage,
1124 one that would help mostly the developer.
1126 CONFIG_SYS_DFU_DATA_BUF_SIZE
1127 Dfu transfer uses a buffer before writing data to the
1128 raw storage device. Make the size (in bytes) of this buffer
1129 configurable. The size of this buffer is also configurable
1130 through the "dfu_bufsiz" environment variable.
1132 CONFIG_SYS_DFU_MAX_FILE_SIZE
1133 When updating files rather than the raw storage device,
1134 we use a static buffer to copy the file into and then write
1135 the buffer once we've been given the whole file. Define
1136 this to the maximum filesize (in bytes) for the buffer.
1137 Default is 4 MiB if undefined.
1139 DFU_DEFAULT_POLL_TIMEOUT
1140 Poll timeout [ms], is the timeout a device can send to the
1141 host. The host must wait for this timeout before sending
1142 a subsequent DFU_GET_STATUS request to the device.
1144 DFU_MANIFEST_POLL_TIMEOUT
1145 Poll timeout [ms], which the device sends to the host when
1146 entering dfuMANIFEST state. Host waits this timeout, before
1147 sending again an USB request to the device.
1149 - Journaling Flash filesystem support:
1151 Define these for a default partition on a NAND device
1153 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1154 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1155 Define these for a default partition on a NOR device
1158 See Kconfig help for available keyboard drivers.
1162 Define this to enable a custom keyboard support.
1163 This simply calls drv_keyboard_init() which must be
1164 defined in your board-specific files. This option is deprecated
1165 and is only used by novena. For new boards, use driver model
1170 Enable the Freescale DIU video driver. Reference boards for
1171 SOCs that have a DIU should define this macro to enable DIU
1172 support, and should also define these other macros:
1177 CONFIG_VIDEO_SW_CURSOR
1178 CONFIG_VGA_AS_SINGLE_DEVICE
1180 CONFIG_VIDEO_BMP_LOGO
1182 The DIU driver will look for the 'video-mode' environment
1183 variable, and if defined, enable the DIU as a console during
1184 boot. See the documentation file doc/README.video for a
1185 description of this variable.
1187 - LCD Support: CONFIG_LCD
1189 Define this to enable LCD support (for output to LCD
1190 display); also select one of the supported displays
1191 by defining one of these:
1195 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1197 CONFIG_NEC_NL6448AC33:
1199 NEC NL6448AC33-18. Active, color, single scan.
1201 CONFIG_NEC_NL6448BC20
1203 NEC NL6448BC20-08. 6.5", 640x480.
1204 Active, color, single scan.
1206 CONFIG_NEC_NL6448BC33_54
1208 NEC NL6448BC33-54. 10.4", 640x480.
1209 Active, color, single scan.
1213 Sharp 320x240. Active, color, single scan.
1214 It isn't 16x9, and I am not sure what it is.
1216 CONFIG_SHARP_LQ64D341
1218 Sharp LQ64D341 display, 640x480.
1219 Active, color, single scan.
1223 HLD1045 display, 640x480.
1224 Active, color, single scan.
1228 Optrex CBL50840-2 NF-FW 99 22 M5
1230 Hitachi LMG6912RPFC-00T
1234 320x240. Black & white.
1236 CONFIG_LCD_ALIGNMENT
1238 Normally the LCD is page-aligned (typically 4KB). If this is
1239 defined then the LCD will be aligned to this value instead.
1240 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1241 here, since it is cheaper to change data cache settings on
1242 a per-section basis.
1247 Sometimes, for example if the display is mounted in portrait
1248 mode or even if it's mounted landscape but rotated by 180degree,
1249 we need to rotate our content of the display relative to the
1250 framebuffer, so that user can read the messages which are
1252 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1253 initialized with a given rotation from "vl_rot" out of
1254 "vidinfo_t" which is provided by the board specific code.
1255 The value for vl_rot is coded as following (matching to
1256 fbcon=rotate:<n> linux-kernel commandline):
1257 0 = no rotation respectively 0 degree
1258 1 = 90 degree rotation
1259 2 = 180 degree rotation
1260 3 = 270 degree rotation
1262 If CONFIG_LCD_ROTATION is not defined, the console will be
1263 initialized with 0degree rotation.
1267 Support drawing of RLE8-compressed bitmaps on the LCD.
1271 Enables an 'i2c edid' command which can read EDID
1272 information over I2C from an attached LCD display.
1274 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1276 If this option is set, the environment is checked for
1277 a variable "splashimage". If found, the usual display
1278 of logo, copyright and system information on the LCD
1279 is suppressed and the BMP image at the address
1280 specified in "splashimage" is loaded instead. The
1281 console is redirected to the "nulldev", too. This
1282 allows for a "silent" boot where a splash screen is
1283 loaded very quickly after power-on.
1285 CONFIG_SPLASHIMAGE_GUARD
1287 If this option is set, then U-Boot will prevent the environment
1288 variable "splashimage" from being set to a problematic address
1289 (see doc/README.displaying-bmps).
1290 This option is useful for targets where, due to alignment
1291 restrictions, an improperly aligned BMP image will cause a data
1292 abort. If you think you will not have problems with unaligned
1293 accesses (for example because your toolchain prevents them)
1294 there is no need to set this option.
1296 CONFIG_SPLASH_SCREEN_ALIGN
1298 If this option is set the splash image can be freely positioned
1299 on the screen. Environment variable "splashpos" specifies the
1300 position as "x,y". If a positive number is given it is used as
1301 number of pixel from left/top. If a negative number is given it
1302 is used as number of pixel from right/bottom. You can also
1303 specify 'm' for centering the image.
1306 setenv splashpos m,m
1307 => image at center of screen
1309 setenv splashpos 30,20
1310 => image at x = 30 and y = 20
1312 setenv splashpos -10,m
1313 => vertically centered image
1314 at x = dspWidth - bmpWidth - 9
1316 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1318 If this option is set, additionally to standard BMP
1319 images, gzipped BMP images can be displayed via the
1320 splashscreen support or the bmp command.
1322 - Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1324 If this option is set, 8-bit RLE compressed BMP images
1325 can be displayed via the splashscreen support or the
1328 - Compression support:
1331 Enabled by default to support gzip compressed images.
1335 If this option is set, support for bzip2 compressed
1336 images is included. If not, only uncompressed and gzip
1337 compressed images are supported.
1339 NOTE: the bzip2 algorithm requires a lot of RAM, so
1340 the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1344 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1346 The clock frequency of the MII bus
1348 CONFIG_PHY_RESET_DELAY
1350 Some PHY like Intel LXT971A need extra delay after
1351 reset before any MII register access is possible.
1352 For such PHY, set this option to the usec delay
1353 required. (minimum 300usec for LXT971A)
1355 CONFIG_PHY_CMD_DELAY (ppc4xx)
1357 Some PHY like Intel LXT971A need extra delay after
1358 command issued before MII status register can be read
1363 Define a default value for the IP address to use for
1364 the default Ethernet interface, in case this is not
1365 determined through e.g. bootp.
1366 (Environment variable "ipaddr")
1368 - Server IP address:
1371 Defines a default value for the IP address of a TFTP
1372 server to contact when using the "tftboot" command.
1373 (Environment variable "serverip")
1375 CONFIG_KEEP_SERVERADDR
1377 Keeps the server's MAC address, in the env 'serveraddr'
1378 for passing to bootargs (like Linux's netconsole option)
1380 - Gateway IP address:
1383 Defines a default value for the IP address of the
1384 default router where packets to other networks are
1386 (Environment variable "gatewayip")
1391 Defines a default value for the subnet mask (or
1392 routing prefix) which is used to determine if an IP
1393 address belongs to the local subnet or needs to be
1394 forwarded through a router.
1395 (Environment variable "netmask")
1397 - BOOTP Recovery Mode:
1398 CONFIG_BOOTP_RANDOM_DELAY
1400 If you have many targets in a network that try to
1401 boot using BOOTP, you may want to avoid that all
1402 systems send out BOOTP requests at precisely the same
1403 moment (which would happen for instance at recovery
1404 from a power failure, when all systems will try to
1405 boot, thus flooding the BOOTP server. Defining
1406 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1407 inserted before sending out BOOTP requests. The
1408 following delays are inserted then:
1410 1st BOOTP request: delay 0 ... 1 sec
1411 2nd BOOTP request: delay 0 ... 2 sec
1412 3rd BOOTP request: delay 0 ... 4 sec
1414 BOOTP requests: delay 0 ... 8 sec
1416 CONFIG_BOOTP_ID_CACHE_SIZE
1418 BOOTP packets are uniquely identified using a 32-bit ID. The
1419 server will copy the ID from client requests to responses and
1420 U-Boot will use this to determine if it is the destination of
1421 an incoming response. Some servers will check that addresses
1422 aren't in use before handing them out (usually using an ARP
1423 ping) and therefore take up to a few hundred milliseconds to
1424 respond. Network congestion may also influence the time it
1425 takes for a response to make it back to the client. If that
1426 time is too long, U-Boot will retransmit requests. In order
1427 to allow earlier responses to still be accepted after these
1428 retransmissions, U-Boot's BOOTP client keeps a small cache of
1429 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1430 cache. The default is to keep IDs for up to four outstanding
1431 requests. Increasing this will allow U-Boot to accept offers
1432 from a BOOTP client in networks with unusually high latency.
1434 - DHCP Advanced Options:
1435 You can fine tune the DHCP functionality by defining
1436 CONFIG_BOOTP_* symbols:
1438 CONFIG_BOOTP_NISDOMAIN
1439 CONFIG_BOOTP_BOOTFILESIZE
1440 CONFIG_BOOTP_SEND_HOSTNAME
1441 CONFIG_BOOTP_NTPSERVER
1442 CONFIG_BOOTP_TIMEOFFSET
1443 CONFIG_BOOTP_VENDOREX
1444 CONFIG_BOOTP_MAY_FAIL
1446 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1447 environment variable, not the BOOTP server.
1449 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1450 after the configured retry count, the call will fail
1451 instead of starting over. This can be used to fail over
1452 to Link-local IP address configuration if the DHCP server
1455 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1456 to do a dynamic update of a DNS server. To do this, they
1457 need the hostname of the DHCP requester.
1458 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1459 of the "hostname" environment variable is passed as
1460 option 12 to the DHCP server.
1462 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1464 A 32bit value in microseconds for a delay between
1465 receiving a "DHCP Offer" and sending the "DHCP Request".
1466 This fixes a problem with certain DHCP servers that don't
1467 respond 100% of the time to a "DHCP request". E.g. On an
1468 AT91RM9200 processor running at 180MHz, this delay needed
1469 to be *at least* 15,000 usec before a Windows Server 2003
1470 DHCP server would reply 100% of the time. I recommend at
1471 least 50,000 usec to be safe. The alternative is to hope
1472 that one of the retries will be successful but note that
1473 the DHCP timeout and retry process takes a longer than
1476 - Link-local IP address negotiation:
1477 Negotiate with other link-local clients on the local network
1478 for an address that doesn't require explicit configuration.
1479 This is especially useful if a DHCP server cannot be guaranteed
1480 to exist in all environments that the device must operate.
1482 See doc/README.link-local for more information.
1484 - MAC address from environment variables
1486 FDT_SEQ_MACADDR_FROM_ENV
1488 Fix-up device tree with MAC addresses fetched sequentially from
1489 environment variables. This config work on assumption that
1490 non-usable ethernet node of device-tree are either not present
1491 or their status has been marked as "disabled".
1494 CONFIG_CDP_DEVICE_ID
1496 The device id used in CDP trigger frames.
1498 CONFIG_CDP_DEVICE_ID_PREFIX
1500 A two character string which is prefixed to the MAC address
1505 A printf format string which contains the ascii name of
1506 the port. Normally is set to "eth%d" which sets
1507 eth0 for the first Ethernet, eth1 for the second etc.
1509 CONFIG_CDP_CAPABILITIES
1511 A 32bit integer which indicates the device capabilities;
1512 0x00000010 for a normal host which does not forwards.
1516 An ascii string containing the version of the software.
1520 An ascii string containing the name of the platform.
1524 A 32bit integer sent on the trigger.
1526 CONFIG_CDP_POWER_CONSUMPTION
1528 A 16bit integer containing the power consumption of the
1529 device in .1 of milliwatts.
1531 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1533 A byte containing the id of the VLAN.
1535 - Status LED: CONFIG_LED_STATUS
1537 Several configurations allow to display the current
1538 status using a LED. For instance, the LED will blink
1539 fast while running U-Boot code, stop blinking as
1540 soon as a reply to a BOOTP request was received, and
1541 start blinking slow once the Linux kernel is running
1542 (supported by a status LED driver in the Linux
1543 kernel). Defining CONFIG_LED_STATUS enables this
1548 CONFIG_LED_STATUS_GPIO
1549 The status LED can be connected to a GPIO pin.
1550 In such cases, the gpio_led driver can be used as a
1551 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1552 to include the gpio_led driver in the U-Boot binary.
1554 CONFIG_GPIO_LED_INVERTED_TABLE
1555 Some GPIO connected LEDs may have inverted polarity in which
1556 case the GPIO high value corresponds to LED off state and
1557 GPIO low value corresponds to LED on state.
1558 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1559 with a list of GPIO LEDs that have inverted polarity.
1561 - I2C Support: CONFIG_SYS_I2C
1563 This enable the NEW i2c subsystem, and will allow you to use
1564 i2c commands at the u-boot command line (as long as you set
1565 CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1566 based realtime clock chips or other i2c devices. See
1567 common/cmd_i2c.c for a description of the command line
1570 ported i2c driver to the new framework:
1571 - drivers/i2c/soft_i2c.c:
1572 - activate first bus with CONFIG_SYS_I2C_SOFT define
1573 CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1574 for defining speed and slave address
1575 - activate second bus with I2C_SOFT_DECLARATIONS2 define
1576 CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1577 for defining speed and slave address
1578 - activate third bus with I2C_SOFT_DECLARATIONS3 define
1579 CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1580 for defining speed and slave address
1581 - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1582 CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1583 for defining speed and slave address
1585 - drivers/i2c/fsl_i2c.c:
1586 - activate i2c driver with CONFIG_SYS_I2C_FSL
1587 define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1588 offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1589 CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1591 - If your board supports a second fsl i2c bus, define
1592 CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1593 CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1594 CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
1597 - drivers/i2c/tegra_i2c.c:
1598 - activate this driver with CONFIG_SYS_I2C_TEGRA
1599 - This driver adds 4 i2c buses with a fix speed from
1600 100000 and the slave addr 0!
1602 - drivers/i2c/ppc4xx_i2c.c
1603 - activate this driver with CONFIG_SYS_I2C_PPC4XX
1604 - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
1605 - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
1607 - drivers/i2c/i2c_mxc.c
1608 - activate this driver with CONFIG_SYS_I2C_MXC
1609 - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
1610 - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
1611 - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
1612 - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
1613 - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
1614 - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
1615 - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
1616 - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
1617 - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
1618 - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
1619 - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
1620 - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
1621 If those defines are not set, default value is 100000
1622 for speed, and 0 for slave.
1624 - drivers/i2c/rcar_i2c.c:
1625 - activate this driver with CONFIG_SYS_I2C_RCAR
1626 - This driver adds 4 i2c buses
1628 - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
1629 - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
1630 - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
1631 - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
1632 - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
1633 - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
1634 - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
1635 - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
1636 - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
1638 - drivers/i2c/sh_i2c.c:
1639 - activate this driver with CONFIG_SYS_I2C_SH
1640 - This driver adds from 2 to 5 i2c buses
1642 - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
1643 - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
1644 - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
1645 - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
1646 - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
1647 - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
1648 - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
1649 - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
1650 - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
1651 - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
1652 - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
1654 - drivers/i2c/omap24xx_i2c.c
1655 - activate this driver with CONFIG_SYS_I2C_OMAP24XX
1656 - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
1657 - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
1658 - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
1659 - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
1660 - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
1661 - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
1662 - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
1663 - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
1664 - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
1665 - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
1667 - drivers/i2c/s3c24x0_i2c.c:
1668 - activate this driver with CONFIG_SYS_I2C_S3C24X0
1669 - This driver adds i2c buses (11 for Exynos5250, Exynos5420
1670 9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
1671 with a fix speed from 100000 and the slave addr 0!
1673 - drivers/i2c/ihs_i2c.c
1674 - activate this driver with CONFIG_SYS_I2C_IHS
1675 - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
1676 - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
1677 - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
1678 - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
1679 - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
1680 - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
1681 - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
1682 - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
1683 - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
1684 - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
1685 - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
1686 - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
1687 - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
1688 - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
1689 - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
1690 - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
1691 - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
1692 - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
1693 - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
1694 - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
1695 - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
1699 CONFIG_SYS_NUM_I2C_BUSES
1700 Hold the number of i2c buses you want to use.
1702 CONFIG_SYS_I2C_DIRECT_BUS
1703 define this, if you don't use i2c muxes on your hardware.
1704 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1707 CONFIG_SYS_I2C_MAX_HOPS
1708 define how many muxes are maximal consecutively connected
1709 on one i2c bus. If you not use i2c muxes, omit this
1712 CONFIG_SYS_I2C_BUSES
1713 hold a list of buses you want to use, only used if
1714 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1715 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1716 CONFIG_SYS_NUM_I2C_BUSES = 9:
1718 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1719 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1720 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1721 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1722 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1723 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1724 {1, {I2C_NULL_HOP}}, \
1725 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1726 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1730 bus 0 on adapter 0 without a mux
1731 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1732 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1733 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1734 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1735 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1736 bus 6 on adapter 1 without a mux
1737 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1738 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1740 If you do not have i2c muxes on your board, omit this define.
1742 - Legacy I2C Support:
1743 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1744 then the following macros need to be defined (examples are
1745 from include/configs/lwmon.h):
1749 (Optional). Any commands necessary to enable the I2C
1750 controller or configure ports.
1752 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1756 The code necessary to make the I2C data line active
1757 (driven). If the data line is open collector, this
1760 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1764 The code necessary to make the I2C data line tri-stated
1765 (inactive). If the data line is open collector, this
1768 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1772 Code that returns true if the I2C data line is high,
1775 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1779 If <bit> is true, sets the I2C data line high. If it
1780 is false, it clears it (low).
1782 eg: #define I2C_SDA(bit) \
1783 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1784 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1788 If <bit> is true, sets the I2C clock line high. If it
1789 is false, it clears it (low).
1791 eg: #define I2C_SCL(bit) \
1792 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1793 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1797 This delay is invoked four times per clock cycle so this
1798 controls the rate of data transfer. The data rate thus
1799 is 1 / (I2C_DELAY * 4). Often defined to be something
1802 #define I2C_DELAY udelay(2)
1804 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1806 If your arch supports the generic GPIO framework (asm/gpio.h),
1807 then you may alternatively define the two GPIOs that are to be
1808 used as SCL / SDA. Any of the previous I2C_xxx macros will
1809 have GPIO-based defaults assigned to them as appropriate.
1811 You should define these to the GPIO value as given directly to
1812 the generic GPIO functions.
1814 CONFIG_SYS_I2C_INIT_BOARD
1816 When a board is reset during an i2c bus transfer
1817 chips might think that the current transfer is still
1818 in progress. On some boards it is possible to access
1819 the i2c SCLK line directly, either by using the
1820 processor pin as a GPIO or by having a second pin
1821 connected to the bus. If this option is defined a
1822 custom i2c_init_board() routine in boards/xxx/board.c
1823 is run early in the boot sequence.
1825 CONFIG_I2C_MULTI_BUS
1827 This option allows the use of multiple I2C buses, each of which
1828 must have a controller. At any point in time, only one bus is
1829 active. To switch to a different bus, use the 'i2c dev' command.
1830 Note that bus numbering is zero-based.
1832 CONFIG_SYS_I2C_NOPROBES
1834 This option specifies a list of I2C devices that will be skipped
1835 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1836 is set, specify a list of bus-device pairs. Otherwise, specify
1837 a 1D array of device addresses
1840 #undef CONFIG_I2C_MULTI_BUS
1841 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1843 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1845 #define CONFIG_I2C_MULTI_BUS
1846 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1848 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1850 CONFIG_SYS_SPD_BUS_NUM
1852 If defined, then this indicates the I2C bus number for DDR SPD.
1853 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1855 CONFIG_SYS_RTC_BUS_NUM
1857 If defined, then this indicates the I2C bus number for the RTC.
1858 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1860 CONFIG_SOFT_I2C_READ_REPEATED_START
1862 defining this will force the i2c_read() function in
1863 the soft_i2c driver to perform an I2C repeated start
1864 between writing the address pointer and reading the
1865 data. If this define is omitted the default behaviour
1866 of doing a stop-start sequence will be used. Most I2C
1867 devices can use either method, but some require one or
1870 - SPI Support: CONFIG_SPI
1872 Enables SPI driver (so far only tested with
1873 SPI EEPROM, also an instance works with Crystal A/D and
1874 D/As on the SACSng board)
1878 Enables a software (bit-bang) SPI driver rather than
1879 using hardware support. This is a general purpose
1880 driver that only requires three general I/O port pins
1881 (two outputs, one input) to function. If this is
1882 defined, the board configuration must define several
1883 SPI configuration items (port pins to use, etc). For
1884 an example, see include/configs/sacsng.h.
1886 CONFIG_SYS_SPI_MXC_WAIT
1887 Timeout for waiting until spi transfer completed.
1888 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1890 - FPGA Support: CONFIG_FPGA
1892 Enables FPGA subsystem.
1894 CONFIG_FPGA_<vendor>
1896 Enables support for specific chip vendors.
1899 CONFIG_FPGA_<family>
1901 Enables support for FPGA family.
1902 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1906 Specify the number of FPGA devices to support.
1908 CONFIG_SYS_FPGA_PROG_FEEDBACK
1910 Enable printing of hash marks during FPGA configuration.
1912 CONFIG_SYS_FPGA_CHECK_BUSY
1914 Enable checks on FPGA configuration interface busy
1915 status by the configuration function. This option
1916 will require a board or device specific function to
1921 If defined, a function that provides delays in the FPGA
1922 configuration driver.
1924 CONFIG_SYS_FPGA_CHECK_CTRLC
1925 Allow Control-C to interrupt FPGA configuration
1927 CONFIG_SYS_FPGA_CHECK_ERROR
1929 Check for configuration errors during FPGA bitfile
1930 loading. For example, abort during Virtex II
1931 configuration if the INIT_B line goes low (which
1932 indicated a CRC error).
1934 CONFIG_SYS_FPGA_WAIT_INIT
1936 Maximum time to wait for the INIT_B line to de-assert
1937 after PROB_B has been de-asserted during a Virtex II
1938 FPGA configuration sequence. The default time is 500
1941 CONFIG_SYS_FPGA_WAIT_BUSY
1943 Maximum time to wait for BUSY to de-assert during
1944 Virtex II FPGA configuration. The default is 5 ms.
1946 CONFIG_SYS_FPGA_WAIT_CONFIG
1948 Time to wait after FPGA configuration. The default is
1951 - Configuration Management:
1955 If defined, this string will be added to the U-Boot
1956 version information (U_BOOT_VERSION)
1958 - Vendor Parameter Protection:
1960 U-Boot considers the values of the environment
1961 variables "serial#" (Board Serial Number) and
1962 "ethaddr" (Ethernet Address) to be parameters that
1963 are set once by the board vendor / manufacturer, and
1964 protects these variables from casual modification by
1965 the user. Once set, these variables are read-only,
1966 and write or delete attempts are rejected. You can
1967 change this behaviour:
1969 If CONFIG_ENV_OVERWRITE is #defined in your config
1970 file, the write protection for vendor parameters is
1971 completely disabled. Anybody can change or delete
1974 Alternatively, if you define _both_ an ethaddr in the
1975 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1976 Ethernet address is installed in the environment,
1977 which can be changed exactly ONCE by the user. [The
1978 serial# is unaffected by this, i. e. it remains
1981 The same can be accomplished in a more flexible way
1982 for any variable by configuring the type of access
1983 to allow for those variables in the ".flags" variable
1984 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1989 Define this variable to enable the reservation of
1990 "protected RAM", i. e. RAM which is not overwritten
1991 by U-Boot. Define CONFIG_PRAM to hold the number of
1992 kB you want to reserve for pRAM. You can overwrite
1993 this default value by defining an environment
1994 variable "pram" to the number of kB you want to
1995 reserve. Note that the board info structure will
1996 still show the full amount of RAM. If pRAM is
1997 reserved, a new environment variable "mem" will
1998 automatically be defined to hold the amount of
1999 remaining RAM in a form that can be passed as boot
2000 argument to Linux, for instance like that:
2002 setenv bootargs ... mem=\${mem}
2005 This way you can tell Linux not to use this memory,
2006 either, which results in a memory region that will
2007 not be affected by reboots.
2009 *WARNING* If your board configuration uses automatic
2010 detection of the RAM size, you must make sure that
2011 this memory test is non-destructive. So far, the
2012 following board configurations are known to be
2015 IVMS8, IVML24, SPD8xx,
2016 HERMES, IP860, RPXlite, LWMON,
2019 - Access to physical memory region (> 4GB)
2020 Some basic support is provided for operations on memory not
2021 normally accessible to U-Boot - e.g. some architectures
2022 support access to more than 4GB of memory on 32-bit
2023 machines using physical address extension or similar.
2024 Define CONFIG_PHYSMEM to access this basic support, which
2025 currently only supports clearing the memory.
2028 CONFIG_NET_RETRY_COUNT
2030 This variable defines the number of retries for
2031 network operations like ARP, RARP, TFTP, or BOOTP
2032 before giving up the operation. If not defined, a
2033 default value of 5 is used.
2037 Timeout waiting for an ARP reply in milliseconds.
2041 Timeout in milliseconds used in NFS protocol.
2042 If you encounter "ERROR: Cannot umount" in nfs command,
2043 try longer timeout such as
2044 #define CONFIG_NFS_TIMEOUT 10000UL
2046 - Command Interpreter:
2047 CONFIG_SYS_PROMPT_HUSH_PS2
2049 This defines the secondary prompt string, which is
2050 printed when the command interpreter needs more input
2051 to complete a command. Usually "> ".
2055 In the current implementation, the local variables
2056 space and global environment variables space are
2057 separated. Local variables are those you define by
2058 simply typing `name=value'. To access a local
2059 variable later on, you have write `$name' or
2060 `${name}'; to execute the contents of a variable
2061 directly type `$name' at the command prompt.
2063 Global environment variables are those you use
2064 setenv/printenv to work with. To run a command stored
2065 in such a variable, you need to use the run command,
2066 and you must not use the '$' sign to access them.
2068 To store commands and special characters in a
2069 variable, please use double quotation marks
2070 surrounding the whole text of the variable, instead
2071 of the backslashes before semicolons and special
2074 - Command Line Editing and History:
2075 CONFIG_CMDLINE_PS_SUPPORT
2077 Enable support for changing the command prompt string
2078 at run-time. Only static string is supported so far.
2079 The string is obtained from environment variables PS1
2082 - Default Environment:
2083 CONFIG_EXTRA_ENV_SETTINGS
2085 Define this to contain any number of null terminated
2086 strings (variable = value pairs) that will be part of
2087 the default environment compiled into the boot image.
2089 For example, place something like this in your
2090 board's config file:
2092 #define CONFIG_EXTRA_ENV_SETTINGS \
2096 Warning: This method is based on knowledge about the
2097 internal format how the environment is stored by the
2098 U-Boot code. This is NOT an official, exported
2099 interface! Although it is unlikely that this format
2100 will change soon, there is no guarantee either.
2101 You better know what you are doing here.
2103 Note: overly (ab)use of the default environment is
2104 discouraged. Make sure to check other ways to preset
2105 the environment like the "source" command or the
2108 CONFIG_DELAY_ENVIRONMENT
2110 Normally the environment is loaded when the board is
2111 initialised so that it is available to U-Boot. This inhibits
2112 that so that the environment is not available until
2113 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2114 this is instead controlled by the value of
2115 /config/load-environment.
2117 - TFTP Fixed UDP Port:
2120 If this is defined, the environment variable tftpsrcp
2121 is used to supply the TFTP UDP source port value.
2122 If tftpsrcp isn't defined, the normal pseudo-random port
2123 number generator is used.
2125 Also, the environment variable tftpdstp is used to supply
2126 the TFTP UDP destination port value. If tftpdstp isn't
2127 defined, the normal port 69 is used.
2129 The purpose for tftpsrcp is to allow a TFTP server to
2130 blindly start the TFTP transfer using the pre-configured
2131 target IP address and UDP port. This has the effect of
2132 "punching through" the (Windows XP) firewall, allowing
2133 the remainder of the TFTP transfer to proceed normally.
2134 A better solution is to properly configure the firewall,
2135 but sometimes that is not allowed.
2137 CONFIG_STANDALONE_LOAD_ADDR
2139 This option defines a board specific value for the
2140 address where standalone program gets loaded, thus
2141 overwriting the architecture dependent default
2144 - Frame Buffer Address:
2147 Define CONFIG_FB_ADDR if you want to use specific
2148 address for frame buffer. This is typically the case
2149 when using a graphics controller has separate video
2150 memory. U-Boot will then place the frame buffer at
2151 the given address instead of dynamically reserving it
2152 in system RAM by calling lcd_setmem(), which grabs
2153 the memory for the frame buffer depending on the
2154 configured panel size.
2156 Please see board_init_f function.
2158 - Automatic software updates via TFTP server
2160 CONFIG_UPDATE_TFTP_CNT_MAX
2161 CONFIG_UPDATE_TFTP_MSEC_MAX
2163 These options enable and control the auto-update feature;
2164 for a more detailed description refer to doc/README.update.
2166 - MTD Support (mtdparts command, UBI support)
2167 CONFIG_MTD_UBI_WL_THRESHOLD
2168 This parameter defines the maximum difference between the highest
2169 erase counter value and the lowest erase counter value of eraseblocks
2170 of UBI devices. When this threshold is exceeded, UBI starts performing
2171 wear leveling by means of moving data from eraseblock with low erase
2172 counter to eraseblocks with high erase counter.
2174 The default value should be OK for SLC NAND flashes, NOR flashes and
2175 other flashes which have eraseblock life-cycle 100000 or more.
2176 However, in case of MLC NAND flashes which typically have eraseblock
2177 life-cycle less than 10000, the threshold should be lessened (e.g.,
2178 to 128 or 256, although it does not have to be power of 2).
2182 CONFIG_MTD_UBI_BEB_LIMIT
2183 This option specifies the maximum bad physical eraseblocks UBI
2184 expects on the MTD device (per 1024 eraseblocks). If the
2185 underlying flash does not admit of bad eraseblocks (e.g. NOR
2186 flash), this value is ignored.
2188 NAND datasheets often specify the minimum and maximum NVM
2189 (Number of Valid Blocks) for the flashes' endurance lifetime.
2190 The maximum expected bad eraseblocks per 1024 eraseblocks
2191 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
2192 which gives 20 for most NANDs (MaxNVB is basically the total
2193 count of eraseblocks on the chip).
2195 To put it differently, if this value is 20, UBI will try to
2196 reserve about 1.9% of physical eraseblocks for bad blocks
2197 handling. And that will be 1.9% of eraseblocks on the entire
2198 NAND chip, not just the MTD partition UBI attaches. This means
2199 that if you have, say, a NAND flash chip admits maximum 40 bad
2200 eraseblocks, and it is split on two MTD partitions of the same
2201 size, UBI will reserve 40 eraseblocks when attaching a
2206 CONFIG_MTD_UBI_FASTMAP
2207 Fastmap is a mechanism which allows attaching an UBI device
2208 in nearly constant time. Instead of scanning the whole MTD device it
2209 only has to locate a checkpoint (called fastmap) on the device.
2210 The on-flash fastmap contains all information needed to attach
2211 the device. Using fastmap makes only sense on large devices where
2212 attaching by scanning takes long. UBI will not automatically install
2213 a fastmap on old images, but you can set the UBI parameter
2214 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
2215 that fastmap-enabled images are still usable with UBI implementations
2216 without fastmap support. On typical flash devices the whole fastmap
2217 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
2219 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
2220 Set this parameter to enable fastmap automatically on images
2224 CONFIG_MTD_UBI_FM_DEBUG
2225 Enable UBI fastmap debug
2230 Enable building of SPL globally.
2233 LDSCRIPT for linking the SPL binary.
2235 CONFIG_SPL_MAX_FOOTPRINT
2236 Maximum size in memory allocated to the SPL, BSS included.
2237 When defined, the linker checks that the actual memory
2238 used by SPL from _start to __bss_end does not exceed it.
2239 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2240 must not be both defined at the same time.
2243 Maximum size of the SPL image (text, data, rodata, and
2244 linker lists sections), BSS excluded.
2245 When defined, the linker checks that the actual size does
2248 CONFIG_SPL_RELOC_TEXT_BASE
2249 Address to relocate to. If unspecified, this is equal to
2250 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
2252 CONFIG_SPL_BSS_START_ADDR
2253 Link address for the BSS within the SPL binary.
2255 CONFIG_SPL_BSS_MAX_SIZE
2256 Maximum size in memory allocated to the SPL BSS.
2257 When defined, the linker checks that the actual memory used
2258 by SPL from __bss_start to __bss_end does not exceed it.
2259 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2260 must not be both defined at the same time.
2263 Adress of the start of the stack SPL will use
2265 CONFIG_SPL_PANIC_ON_RAW_IMAGE
2266 When defined, SPL will panic() if the image it has
2267 loaded does not have a signature.
2268 Defining this is useful when code which loads images
2269 in SPL cannot guarantee that absolutely all read errors
2271 An example is the LPC32XX MLC NAND driver, which will
2272 consider that a completely unreadable NAND block is bad,
2273 and thus should be skipped silently.
2275 CONFIG_SPL_RELOC_STACK
2276 Adress of the start of the stack SPL will use after
2277 relocation. If unspecified, this is equal to
2280 CONFIG_SYS_SPL_MALLOC_START
2281 Starting address of the malloc pool used in SPL.
2282 When this option is set the full malloc is used in SPL and
2283 it is set up by spl_init() and before that, the simple malloc()
2284 can be used if CONFIG_SYS_MALLOC_F is defined.
2286 CONFIG_SYS_SPL_MALLOC_SIZE
2287 The size of the malloc pool used in SPL.
2290 Enable booting directly to an OS from SPL.
2291 See also: doc/README.falcon
2293 CONFIG_SPL_DISPLAY_PRINT
2294 For ARM, enable an optional function to print more information
2295 about the running system.
2297 CONFIG_SPL_INIT_MINIMAL
2298 Arch init code should be built for a very small image
2300 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
2301 Partition on the MMC to load U-Boot from when the MMC is being
2304 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
2305 Sector to load kernel uImage from when MMC is being
2306 used in raw mode (for Falcon mode)
2308 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
2309 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
2310 Sector and number of sectors to load kernel argument
2311 parameters from when MMC is being used in raw mode
2314 CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
2315 Partition on the MMC to load U-Boot from when the MMC is being
2318 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
2319 Filename to read to load U-Boot when reading from filesystem
2321 CONFIG_SPL_FS_LOAD_KERNEL_NAME
2322 Filename to read to load kernel uImage when reading
2323 from filesystem (for Falcon mode)
2325 CONFIG_SPL_FS_LOAD_ARGS_NAME
2326 Filename to read to load kernel argument parameters
2327 when reading from filesystem (for Falcon mode)
2329 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
2330 Set this for NAND SPL on PPC mpc83xx targets, so that
2331 start.S waits for the rest of the SPL to load before
2332 continuing (the hardware starts execution after just
2333 loading the first page rather than the full 4K).
2335 CONFIG_SPL_SKIP_RELOCATE
2336 Avoid SPL relocation
2338 CONFIG_SPL_NAND_BASE
2339 Include nand_base.c in the SPL. Requires
2340 CONFIG_SPL_NAND_DRIVERS.
2342 CONFIG_SPL_NAND_DRIVERS
2343 SPL uses normal NAND drivers, not minimal drivers.
2345 CONFIG_SPL_NAND_IDENT
2346 SPL uses the chip ID list to identify the NAND flash.
2347 Requires CONFIG_SPL_NAND_BASE.
2350 Include standard software ECC in the SPL
2352 CONFIG_SPL_NAND_SIMPLE
2353 Support for NAND boot using simple NAND drivers that
2354 expose the cmd_ctrl() interface.
2357 Support for a lightweight UBI (fastmap) scanner and
2360 CONFIG_SPL_NAND_RAW_ONLY
2361 Support to boot only raw u-boot.bin images. Use this only
2362 if you need to save space.
2364 CONFIG_SPL_COMMON_INIT_DDR
2365 Set for common ddr init with serial presence detect in
2368 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2369 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2370 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2371 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2372 CONFIG_SYS_NAND_ECCBYTES
2373 Defines the size and behavior of the NAND that SPL uses
2376 CONFIG_SYS_NAND_U_BOOT_OFFS
2377 Location in NAND to read U-Boot from
2379 CONFIG_SYS_NAND_U_BOOT_DST
2380 Location in memory to load U-Boot to
2382 CONFIG_SYS_NAND_U_BOOT_SIZE
2383 Size of image to load
2385 CONFIG_SYS_NAND_U_BOOT_START
2386 Entry point in loaded image to jump to
2388 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2389 Define this if you need to first read the OOB and then the
2390 data. This is used, for example, on davinci platforms.
2392 CONFIG_SPL_RAM_DEVICE
2393 Support for running image already present in ram, in SPL binary
2396 Image offset to which the SPL should be padded before appending
2397 the SPL payload. By default, this is defined as
2398 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2399 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2400 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2403 Final target image containing SPL and payload. Some SPLs
2404 use an arch-specific makefile fragment instead, for
2405 example if more than one image needs to be produced.
2407 CONFIG_SPL_FIT_PRINT
2408 Printing information about a FIT image adds quite a bit of
2409 code to SPL. So this is normally disabled in SPL. Use this
2410 option to re-enable it. This will affect the output of the
2411 bootm command when booting a FIT image.
2415 Enable building of TPL globally.
2418 Image offset to which the TPL should be padded before appending
2419 the TPL payload. By default, this is defined as
2420 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2421 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2422 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2424 - Interrupt support (PPC):
2426 There are common interrupt_init() and timer_interrupt()
2427 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2428 for CPU specific initialization. interrupt_init_cpu()
2429 should set decrementer_count to appropriate value. If
2430 CPU resets decrementer automatically after interrupt
2431 (ppc4xx) it should set decrementer_count to zero.
2432 timer_interrupt() calls timer_interrupt_cpu() for CPU
2433 specific handling. If board has watchdog / status_led
2434 / other_activity_monitor it works automatically from
2435 general timer_interrupt().
2438 Board initialization settings:
2439 ------------------------------
2441 During Initialization u-boot calls a number of board specific functions
2442 to allow the preparation of board specific prerequisites, e.g. pin setup
2443 before drivers are initialized. To enable these callbacks the
2444 following configuration macros have to be defined. Currently this is
2445 architecture specific, so please check arch/your_architecture/lib/board.c
2446 typically in board_init_f() and board_init_r().
2448 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2449 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2450 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2451 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2453 Configuration Settings:
2454 -----------------------
2456 - CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2457 Optionally it can be defined to support 64-bit memory commands.
2459 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2460 undefine this when you're short of memory.
2462 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2463 width of the commands listed in the 'help' command output.
2465 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2466 prompt for user input.
2468 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2470 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2472 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2474 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2475 the application (usually a Linux kernel) when it is
2478 - CONFIG_SYS_BAUDRATE_TABLE:
2479 List of legal baudrate settings for this board.
2481 - CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2482 Begin and End addresses of the area used by the
2485 - CONFIG_SYS_MEMTEST_SCRATCH:
2486 Scratch address used by the alternate memory test
2487 You only need to set this if address zero isn't writeable
2489 - CONFIG_SYS_MEM_RESERVE_SECURE
2490 Only implemented for ARMv8 for now.
2491 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2492 is substracted from total RAM and won't be reported to OS.
2493 This memory can be used as secure memory. A variable
2494 gd->arch.secure_ram is used to track the location. In systems
2495 the RAM base is not zero, or RAM is divided into banks,
2496 this variable needs to be recalcuated to get the address.
2498 - CONFIG_SYS_MEM_TOP_HIDE:
2499 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2500 this specified memory area will get subtracted from the top
2501 (end) of RAM and won't get "touched" at all by U-Boot. By
2502 fixing up gd->ram_size the Linux kernel should gets passed
2503 the now "corrected" memory size and won't touch it either.
2504 This should work for arch/ppc and arch/powerpc. Only Linux
2505 board ports in arch/powerpc with bootwrapper support that
2506 recalculate the memory size from the SDRAM controller setup
2507 will have to get fixed in Linux additionally.
2509 This option can be used as a workaround for the 440EPx/GRx
2510 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2513 WARNING: Please make sure that this value is a multiple of
2514 the Linux page size (normally 4k). If this is not the case,
2515 then the end address of the Linux memory will be located at a
2516 non page size aligned address and this could cause major
2519 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2520 Enable temporary baudrate change while serial download
2522 - CONFIG_SYS_SDRAM_BASE:
2523 Physical start address of SDRAM. _Must_ be 0 here.
2525 - CONFIG_SYS_FLASH_BASE:
2526 Physical start address of Flash memory.
2528 - CONFIG_SYS_MONITOR_BASE:
2529 Physical start address of boot monitor code (set by
2530 make config files to be same as the text base address
2531 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2532 CONFIG_SYS_FLASH_BASE when booting from flash.
2534 - CONFIG_SYS_MONITOR_LEN:
2535 Size of memory reserved for monitor code, used to
2536 determine _at_compile_time_ (!) if the environment is
2537 embedded within the U-Boot image, or in a separate
2540 - CONFIG_SYS_MALLOC_LEN:
2541 Size of DRAM reserved for malloc() use.
2543 - CONFIG_SYS_MALLOC_F_LEN
2544 Size of the malloc() pool for use before relocation. If
2545 this is defined, then a very simple malloc() implementation
2546 will become available before relocation. The address is just
2547 below the global data, and the stack is moved down to make
2550 This feature allocates regions with increasing addresses
2551 within the region. calloc() is supported, but realloc()
2552 is not available. free() is supported but does nothing.
2553 The memory will be freed (or in fact just forgotten) when
2554 U-Boot relocates itself.
2556 - CONFIG_SYS_MALLOC_SIMPLE
2557 Provides a simple and small malloc() and calloc() for those
2558 boards which do not use the full malloc in SPL (which is
2559 enabled with CONFIG_SYS_SPL_MALLOC_START).
2561 - CONFIG_SYS_NONCACHED_MEMORY:
2562 Size of non-cached memory area. This area of memory will be
2563 typically located right below the malloc() area and mapped
2564 uncached in the MMU. This is useful for drivers that would
2565 otherwise require a lot of explicit cache maintenance. For
2566 some drivers it's also impossible to properly maintain the
2567 cache. For example if the regions that need to be flushed
2568 are not a multiple of the cache-line size, *and* padding
2569 cannot be allocated between the regions to align them (i.e.
2570 if the HW requires a contiguous array of regions, and the
2571 size of each region is not cache-aligned), then a flush of
2572 one region may result in overwriting data that hardware has
2573 written to another region in the same cache-line. This can
2574 happen for example in network drivers where descriptors for
2575 buffers are typically smaller than the CPU cache-line (e.g.
2576 16 bytes vs. 32 or 64 bytes).
2578 Non-cached memory is only supported on 32-bit ARM at present.
2580 - CONFIG_SYS_BOOTM_LEN:
2581 Normally compressed uImages are limited to an
2582 uncompressed size of 8 MBytes. If this is not enough,
2583 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2584 to adjust this setting to your needs.
2586 - CONFIG_SYS_BOOTMAPSZ:
2587 Maximum size of memory mapped by the startup code of
2588 the Linux kernel; all data that must be processed by
2589 the Linux kernel (bd_info, boot arguments, FDT blob if
2590 used) must be put below this limit, unless "bootm_low"
2591 environment variable is defined and non-zero. In such case
2592 all data for the Linux kernel must be between "bootm_low"
2593 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2594 variable "bootm_mapsize" will override the value of
2595 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2596 then the value in "bootm_size" will be used instead.
2598 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2599 Enable initrd_high functionality. If defined then the
2600 initrd_high feature is enabled and the bootm ramdisk subcommand
2603 - CONFIG_SYS_BOOT_GET_CMDLINE:
2604 Enables allocating and saving kernel cmdline in space between
2605 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2607 - CONFIG_SYS_BOOT_GET_KBD:
2608 Enables allocating and saving a kernel copy of the bd_info in
2609 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2611 - CONFIG_SYS_MAX_FLASH_BANKS:
2612 Max number of Flash memory banks
2614 - CONFIG_SYS_MAX_FLASH_SECT:
2615 Max number of sectors on a Flash chip
2617 - CONFIG_SYS_FLASH_ERASE_TOUT:
2618 Timeout for Flash erase operations (in ms)
2620 - CONFIG_SYS_FLASH_WRITE_TOUT:
2621 Timeout for Flash write operations (in ms)
2623 - CONFIG_SYS_FLASH_LOCK_TOUT
2624 Timeout for Flash set sector lock bit operation (in ms)
2626 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2627 Timeout for Flash clear lock bits operation (in ms)
2629 - CONFIG_SYS_FLASH_PROTECTION
2630 If defined, hardware flash sectors protection is used
2631 instead of U-Boot software protection.
2633 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2635 Enable TFTP transfers directly to flash memory;
2636 without this option such a download has to be
2637 performed in two steps: (1) download to RAM, and (2)
2638 copy from RAM to flash.
2640 The two-step approach is usually more reliable, since
2641 you can check if the download worked before you erase
2642 the flash, but in some situations (when system RAM is
2643 too limited to allow for a temporary copy of the
2644 downloaded image) this option may be very useful.
2646 - CONFIG_SYS_FLASH_CFI:
2647 Define if the flash driver uses extra elements in the
2648 common flash structure for storing flash geometry.
2650 - CONFIG_FLASH_CFI_DRIVER
2651 This option also enables the building of the cfi_flash driver
2652 in the drivers directory
2654 - CONFIG_FLASH_CFI_MTD
2655 This option enables the building of the cfi_mtd driver
2656 in the drivers directory. The driver exports CFI flash
2659 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2660 Use buffered writes to flash.
2662 - CONFIG_FLASH_SPANSION_S29WS_N
2663 s29ws-n MirrorBit flash has non-standard addresses for buffered
2666 - CONFIG_SYS_FLASH_QUIET_TEST
2667 If this option is defined, the common CFI flash doesn't
2668 print it's warning upon not recognized FLASH banks. This
2669 is useful, if some of the configured banks are only
2670 optionally available.
2672 - CONFIG_FLASH_SHOW_PROGRESS
2673 If defined (must be an integer), print out countdown
2674 digits and dots. Recommended value: 45 (9..1) for 80
2675 column displays, 15 (3..1) for 40 column displays.
2677 - CONFIG_FLASH_VERIFY
2678 If defined, the content of the flash (destination) is compared
2679 against the source after the write operation. An error message
2680 will be printed when the contents are not identical.
2681 Please note that this option is useless in nearly all cases,
2682 since such flash programming errors usually are detected earlier
2683 while unprotecting/erasing/programming. Please only enable
2684 this option if you really know what you are doing.
2686 - CONFIG_SYS_RX_ETH_BUFFER:
2687 Defines the number of Ethernet receive buffers. On some
2688 Ethernet controllers it is recommended to set this value
2689 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2690 buffers can be full shortly after enabling the interface
2691 on high Ethernet traffic.
2692 Defaults to 4 if not defined.
2694 - CONFIG_ENV_MAX_ENTRIES
2696 Maximum number of entries in the hash table that is used
2697 internally to store the environment settings. The default
2698 setting is supposed to be generous and should work in most
2699 cases. This setting can be used to tune behaviour; see
2700 lib/hashtable.c for details.
2702 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2703 - CONFIG_ENV_FLAGS_LIST_STATIC
2704 Enable validation of the values given to environment variables when
2705 calling env set. Variables can be restricted to only decimal,
2706 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2707 the variables can also be restricted to IP address or MAC address.
2709 The format of the list is:
2710 type_attribute = [s|d|x|b|i|m]
2711 access_attribute = [a|r|o|c]
2712 attributes = type_attribute[access_attribute]
2713 entry = variable_name[:attributes]
2716 The type attributes are:
2717 s - String (default)
2720 b - Boolean ([1yYtT|0nNfF])
2724 The access attributes are:
2730 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2731 Define this to a list (string) to define the ".flags"
2732 environment variable in the default or embedded environment.
2734 - CONFIG_ENV_FLAGS_LIST_STATIC
2735 Define this to a list (string) to define validation that
2736 should be done if an entry is not found in the ".flags"
2737 environment variable. To override a setting in the static
2738 list, simply add an entry for the same variable name to the
2741 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2742 regular expression. This allows multiple variables to define the same
2743 flags without explicitly listing them for each variable.
2745 - CONFIG_ENV_ACCESS_IGNORE_FORCE
2746 If defined, don't allow the -f switch to env set override variable
2749 The following definitions that deal with the placement and management
2750 of environment data (variable area); in general, we support the
2751 following configurations:
2753 - CONFIG_BUILD_ENVCRC:
2755 Builds up envcrc with the target environment so that external utils
2756 may easily extract it and embed it in final U-Boot images.
2758 BE CAREFUL! The first access to the environment happens quite early
2759 in U-Boot initialization (when we try to get the setting of for the
2760 console baudrate). You *MUST* have mapped your NVRAM area then, or
2763 Please note that even with NVRAM we still use a copy of the
2764 environment in RAM: we could work on NVRAM directly, but we want to
2765 keep settings there always unmodified except somebody uses "saveenv"
2766 to save the current settings.
2768 BE CAREFUL! For some special cases, the local device can not use
2769 "saveenv" command. For example, the local device will get the
2770 environment stored in a remote NOR flash by SRIO or PCIE link,
2771 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2773 - CONFIG_NAND_ENV_DST
2775 Defines address in RAM to which the nand_spl code should copy the
2776 environment. If redundant environment is used, it will be copied to
2777 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2779 Please note that the environment is read-only until the monitor
2780 has been relocated to RAM and a RAM copy of the environment has been
2781 created; also, when using EEPROM you will have to use env_get_f()
2782 until then to read environment variables.
2784 The environment is protected by a CRC32 checksum. Before the monitor
2785 is relocated into RAM, as a result of a bad CRC you will be working
2786 with the compiled-in default environment - *silently*!!! [This is
2787 necessary, because the first environment variable we need is the
2788 "baudrate" setting for the console - if we have a bad CRC, we don't
2789 have any device yet where we could complain.]
2791 Note: once the monitor has been relocated, then it will complain if
2792 the default environment is used; a new CRC is computed as soon as you
2793 use the "saveenv" command to store a valid environment.
2795 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2796 Echo the inverted Ethernet link state to the fault LED.
2798 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2799 also needs to be defined.
2801 - CONFIG_SYS_FAULT_MII_ADDR:
2802 MII address of the PHY to check for the Ethernet link state.
2804 - CONFIG_NS16550_MIN_FUNCTIONS:
2805 Define this if you desire to only have use of the NS16550_init
2806 and NS16550_putc functions for the serial driver located at
2807 drivers/serial/ns16550.c. This option is useful for saving
2808 space for already greatly restricted images, including but not
2809 limited to NAND_SPL configurations.
2811 - CONFIG_DISPLAY_BOARDINFO
2812 Display information about the board that U-Boot is running on
2813 when U-Boot starts up. The board function checkboard() is called
2816 - CONFIG_DISPLAY_BOARDINFO_LATE
2817 Similar to the previous option, but display this information
2818 later, once stdio is running and output goes to the LCD, if
2821 - CONFIG_BOARD_SIZE_LIMIT:
2822 Maximum size of the U-Boot image. When defined, the
2823 build system checks that the actual size does not
2826 Low Level (hardware related) configuration options:
2827 ---------------------------------------------------
2829 - CONFIG_SYS_CACHELINE_SIZE:
2830 Cache Line Size of the CPU.
2832 - CONFIG_SYS_CCSRBAR_DEFAULT:
2833 Default (power-on reset) physical address of CCSR on Freescale
2836 - CONFIG_SYS_CCSRBAR:
2837 Virtual address of CCSR. On a 32-bit build, this is typically
2838 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2840 - CONFIG_SYS_CCSRBAR_PHYS:
2841 Physical address of CCSR. CCSR can be relocated to a new
2842 physical address, if desired. In this case, this macro should
2843 be set to that address. Otherwise, it should be set to the
2844 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2845 is typically relocated on 36-bit builds. It is recommended
2846 that this macro be defined via the _HIGH and _LOW macros:
2848 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2849 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2851 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2852 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2853 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2854 used in assembly code, so it must not contain typecasts or
2855 integer size suffixes (e.g. "ULL").
2857 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2858 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2859 used in assembly code, so it must not contain typecasts or
2860 integer size suffixes (e.g. "ULL").
2862 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2863 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2864 forced to a value that ensures that CCSR is not relocated.
2866 - Floppy Disk Support:
2867 CONFIG_SYS_FDC_DRIVE_NUMBER
2869 the default drive number (default value 0)
2871 CONFIG_SYS_ISA_IO_STRIDE
2873 defines the spacing between FDC chipset registers
2876 CONFIG_SYS_ISA_IO_OFFSET
2878 defines the offset of register from address. It
2879 depends on which part of the data bus is connected to
2880 the FDC chipset. (default value 0)
2882 If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
2883 CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
2886 if CONFIG_SYS_FDC_HW_INIT is defined, then the function
2887 fdc_hw_init() is called at the beginning of the FDC
2888 setup. fdc_hw_init() must be provided by the board
2889 source code. It is used to make hardware-dependent
2893 Most IDE controllers were designed to be connected with PCI
2894 interface. Only few of them were designed for AHB interface.
2895 When software is doing ATA command and data transfer to
2896 IDE devices through IDE-AHB controller, some additional
2897 registers accessing to these kind of IDE-AHB controller
2900 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2901 DO NOT CHANGE unless you know exactly what you're
2902 doing! (11-4) [MPC8xx systems only]
2904 - CONFIG_SYS_INIT_RAM_ADDR:
2906 Start address of memory area that can be used for
2907 initial data and stack; please note that this must be
2908 writable memory that is working WITHOUT special
2909 initialization, i. e. you CANNOT use normal RAM which
2910 will become available only after programming the
2911 memory controller and running certain initialization
2914 U-Boot uses the following memory types:
2915 - MPC8xx: IMMR (internal memory of the CPU)
2917 - CONFIG_SYS_GBL_DATA_OFFSET:
2919 Offset of the initial data structure in the memory
2920 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2921 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2922 data is located at the end of the available space
2923 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2924 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2925 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2926 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2929 On the MPC824X (or other systems that use the data
2930 cache for initial memory) the address chosen for
2931 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2932 point to an otherwise UNUSED address space between
2933 the top of RAM and the start of the PCI space.
2935 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2937 - CONFIG_SYS_OR_TIMING_SDRAM:
2940 - CONFIG_SYS_MAMR_PTA:
2941 periodic timer for refresh
2943 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2944 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2945 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2946 CONFIG_SYS_BR1_PRELIM:
2947 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2949 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2950 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2951 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2952 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2954 - CONFIG_PCI_ENUM_ONLY
2955 Only scan through and get the devices on the buses.
2956 Don't do any setup work, presumably because someone or
2957 something has already done it, and we don't need to do it
2958 a second time. Useful for platforms that are pre-booted
2959 by coreboot or similar.
2961 - CONFIG_PCI_INDIRECT_BRIDGE:
2962 Enable support for indirect PCI bridges.
2965 Chip has SRIO or not
2968 Board has SRIO 1 port available
2971 Board has SRIO 2 port available
2973 - CONFIG_SRIO_PCIE_BOOT_MASTER
2974 Board can support master function for Boot from SRIO and PCIE
2976 - CONFIG_SYS_SRIOn_MEM_VIRT:
2977 Virtual Address of SRIO port 'n' memory region
2979 - CONFIG_SYS_SRIOn_MEM_PHYS:
2980 Physical Address of SRIO port 'n' memory region
2982 - CONFIG_SYS_SRIOn_MEM_SIZE:
2983 Size of SRIO port 'n' memory region
2985 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2986 Defined to tell the NAND controller that the NAND chip is using
2988 Not all NAND drivers use this symbol.
2989 Example of drivers that use it:
2990 - drivers/mtd/nand/raw/ndfc.c
2991 - drivers/mtd/nand/raw/mxc_nand.c
2993 - CONFIG_SYS_NDFC_EBC0_CFG
2994 Sets the EBC0_CFG register for the NDFC. If not defined
2995 a default value will be used.
2998 Get DDR timing information from an I2C EEPROM. Common
2999 with pluggable memory modules such as SODIMMs
3002 I2C address of the SPD EEPROM
3004 - CONFIG_SYS_SPD_BUS_NUM
3005 If SPD EEPROM is on an I2C bus other than the first
3006 one, specify here. Note that the value must resolve
3007 to something your driver can deal with.
3009 - CONFIG_SYS_DDR_RAW_TIMING
3010 Get DDR timing information from other than SPD. Common with
3011 soldered DDR chips onboard without SPD. DDR raw timing
3012 parameters are extracted from datasheet and hard-coded into
3013 header files or board specific files.
3015 - CONFIG_FSL_DDR_INTERACTIVE
3016 Enable interactive DDR debugging. See doc/README.fsl-ddr.
3018 - CONFIG_FSL_DDR_SYNC_REFRESH
3019 Enable sync of refresh for multiple controllers.
3021 - CONFIG_FSL_DDR_BIST
3022 Enable built-in memory test for Freescale DDR controllers.
3024 - CONFIG_SYS_83XX_DDR_USES_CS0
3025 Only for 83xx systems. If specified, then DDR should
3026 be configured using CS0 and CS1 instead of CS2 and CS3.
3029 Enable RMII mode for all FECs.
3030 Note that this is a global option, we can't
3031 have one FEC in standard MII mode and another in RMII mode.
3033 - CONFIG_CRC32_VERIFY
3034 Add a verify option to the crc32 command.
3037 => crc32 -v <address> <count> <crc32>
3039 Where address/count indicate a memory area
3040 and crc32 is the correct crc32 which the
3044 Add the "loopw" memory command. This only takes effect if
3045 the memory commands are activated globally (CONFIG_CMD_MEMORY).
3048 Add the "mdc" and "mwc" memory commands. These are cyclic
3053 This command will print 4 bytes (10,11,12,13) each 500 ms.
3055 => mwc.l 100 12345678 10
3056 This command will write 12345678 to address 100 all 10 ms.
3058 This only takes effect if the memory commands are activated
3059 globally (CONFIG_CMD_MEMORY).
3061 - CONFIG_SKIP_LOWLEVEL_INIT
3062 [ARM, NDS32, MIPS, RISC-V only] If this variable is defined, then certain
3063 low level initializations (like setting up the memory
3064 controller) are omitted and/or U-Boot does not
3065 relocate itself into RAM.
3067 Normally this variable MUST NOT be defined. The only
3068 exception is when U-Boot is loaded (to RAM) by some
3069 other boot loader or by a debugger which performs
3070 these initializations itself.
3072 - CONFIG_SKIP_LOWLEVEL_INIT_ONLY
3073 [ARM926EJ-S only] This allows just the call to lowlevel_init()
3074 to be skipped. The normal CP15 init (such as enabling the
3075 instruction cache) is still performed.
3078 Modifies the behaviour of start.S when compiling a loader
3079 that is executed before the actual U-Boot. E.g. when
3080 compiling a NAND SPL.
3083 Modifies the behaviour of start.S when compiling a loader
3084 that is executed after the SPL and before the actual U-Boot.
3085 It is loaded by the SPL.
3087 - CONFIG_SYS_MPC85XX_NO_RESETVEC
3088 Only for 85xx systems. If this variable is specified, the section
3089 .resetvec is not kept and the section .bootpg is placed in the
3090 previous 4k of the .text section.
3092 - CONFIG_ARCH_MAP_SYSMEM
3093 Generally U-Boot (and in particular the md command) uses
3094 effective address. It is therefore not necessary to regard
3095 U-Boot address as virtual addresses that need to be translated
3096 to physical addresses. However, sandbox requires this, since
3097 it maintains its own little RAM buffer which contains all
3098 addressable memory. This option causes some memory accesses
3099 to be mapped through map_sysmem() / unmap_sysmem().
3101 - CONFIG_X86_RESET_VECTOR
3102 If defined, the x86 reset vector code is included. This is not
3103 needed when U-Boot is running from Coreboot.
3105 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
3106 Option to disable subpage write in NAND driver
3107 driver that uses this:
3108 drivers/mtd/nand/raw/davinci_nand.c
3110 Freescale QE/FMAN Firmware Support:
3111 -----------------------------------
3113 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3114 loading of "firmware", which is encoded in the QE firmware binary format.
3115 This firmware often needs to be loaded during U-Boot booting, so macros
3116 are used to identify the storage device (NOR flash, SPI, etc) and the address
3119 - CONFIG_SYS_FMAN_FW_ADDR
3120 The address in the storage device where the FMAN microcode is located. The
3121 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3124 - CONFIG_SYS_QE_FW_ADDR
3125 The address in the storage device where the QE microcode is located. The
3126 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
3129 - CONFIG_SYS_QE_FMAN_FW_LENGTH
3130 The maximum possible size of the firmware. The firmware binary format
3131 has a field that specifies the actual size of the firmware, but it
3132 might not be possible to read any part of the firmware unless some
3133 local storage is allocated to hold the entire firmware first.
3135 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
3136 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3137 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
3138 virtual address in NOR flash.
3140 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
3141 Specifies that QE/FMAN firmware is located in NAND flash.
3142 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3144 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
3145 Specifies that QE/FMAN firmware is located on the primary SD/MMC
3146 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3148 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3149 Specifies that QE/FMAN firmware is located in the remote (master)
3150 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3151 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
3152 window->master inbound window->master LAW->the ucode address in
3153 master's memory space.
3155 Freescale Layerscape Management Complex Firmware Support:
3156 ---------------------------------------------------------
3157 The Freescale Layerscape Management Complex (MC) supports the loading of
3159 This firmware often needs to be loaded during U-Boot booting, so macros
3160 are used to identify the storage device (NOR flash, SPI, etc) and the address
3163 - CONFIG_FSL_MC_ENET
3164 Enable the MC driver for Layerscape SoCs.
3166 Freescale Layerscape Debug Server Support:
3167 -------------------------------------------
3168 The Freescale Layerscape Debug Server Support supports the loading of
3169 "Debug Server firmware" and triggering SP boot-rom.
3170 This firmware often needs to be loaded during U-Boot booting.
3172 - CONFIG_SYS_MC_RSV_MEM_ALIGN
3173 Define alignment of reserved memory MC requires
3178 In order to achieve reproducible builds, timestamps used in the U-Boot build
3179 process have to be set to a fixed value.
3181 This is done using the SOURCE_DATE_EPOCH environment variable.
3182 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
3183 option for U-Boot or an environment variable in U-Boot.
3185 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
3187 Building the Software:
3188 ======================
3190 Building U-Boot has been tested in several native build environments
3191 and in many different cross environments. Of course we cannot support
3192 all possibly existing versions of cross development tools in all
3193 (potentially obsolete) versions. In case of tool chain problems we
3194 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3195 which is extensively used to build and test U-Boot.
3197 If you are not using a native environment, it is assumed that you
3198 have GNU cross compiling tools available in your path. In this case,
3199 you must set the environment variable CROSS_COMPILE in your shell.
3200 Note that no changes to the Makefile or any other source files are
3201 necessary. For example using the ELDK on a 4xx CPU, please enter:
3203 $ CROSS_COMPILE=ppc_4xx-
3204 $ export CROSS_COMPILE
3206 Note: If you wish to generate Windows versions of the utilities in
3207 the tools directory you can use the MinGW toolchain
3208 (http://www.mingw.org). Set your HOST tools to the MinGW
3209 toolchain and execute 'make tools'. For example:
3211 $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3213 Binaries such as tools/mkimage.exe will be created which can
3214 be executed on computers running Windows.
3216 U-Boot is intended to be simple to build. After installing the
3217 sources you must configure U-Boot for one specific board type. This
3222 where "NAME_defconfig" is the name of one of the existing configu-
3223 rations; see boards.cfg for supported names.
3225 Note: for some board special configuration names may exist; check if
3226 additional information is available from the board vendor; for
3227 instance, the TQM823L systems are available without (standard)
3228 or with LCD support. You can select such additional "features"
3229 when choosing the configuration, i. e.
3231 make TQM823L_defconfig
3232 - will configure for a plain TQM823L, i. e. no LCD support
3234 make TQM823L_LCD_defconfig
3235 - will configure for a TQM823L with U-Boot console on LCD
3240 Finally, type "make all", and you should get some working U-Boot
3241 images ready for download to / installation on your system:
3243 - "u-boot.bin" is a raw binary image
3244 - "u-boot" is an image in ELF binary format
3245 - "u-boot.srec" is in Motorola S-Record format
3247 By default the build is performed locally and the objects are saved
3248 in the source directory. One of the two methods can be used to change
3249 this behavior and build U-Boot to some external directory:
3251 1. Add O= to the make command line invocations:
3253 make O=/tmp/build distclean
3254 make O=/tmp/build NAME_defconfig
3255 make O=/tmp/build all
3257 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
3259 export KBUILD_OUTPUT=/tmp/build
3264 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
3267 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
3268 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
3269 For example to treat all compiler warnings as errors:
3271 make KCFLAGS=-Werror
3273 Please be aware that the Makefiles assume you are using GNU make, so
3274 for instance on NetBSD you might need to use "gmake" instead of
3278 If the system board that you have is not listed, then you will need
3279 to port U-Boot to your hardware platform. To do this, follow these
3282 1. Create a new directory to hold your board specific code. Add any
3283 files you need. In your board directory, you will need at least
3284 the "Makefile" and a "<board>.c".
3285 2. Create a new configuration file "include/configs/<board>.h" for
3287 3. If you're porting U-Boot to a new CPU, then also create a new
3288 directory to hold your CPU specific code. Add any files you need.
3289 4. Run "make <board>_defconfig" with your new name.
3290 5. Type "make", and you should get a working "u-boot.srec" file
3291 to be installed on your target system.
3292 6. Debug and solve any problems that might arise.
3293 [Of course, this last step is much harder than it sounds.]
3296 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3297 ==============================================================
3299 If you have modified U-Boot sources (for instance added a new board
3300 or support for new devices, a new CPU, etc.) you are expected to
3301 provide feedback to the other developers. The feedback normally takes
3302 the form of a "patch", i. e. a context diff against a certain (latest
3303 official or latest in the git repository) version of U-Boot sources.
3305 But before you submit such a patch, please verify that your modifi-
3306 cation did not break existing code. At least make sure that *ALL* of
3307 the supported boards compile WITHOUT ANY compiler warnings. To do so,
3308 just run the buildman script (tools/buildman/buildman), which will
3309 configure and build U-Boot for ALL supported system. Be warned, this
3310 will take a while. Please see the buildman README, or run 'buildman -H'
3314 See also "U-Boot Porting Guide" below.
3317 Monitor Commands - Overview:
3318 ============================
3320 go - start application at address 'addr'
3321 run - run commands in an environment variable
3322 bootm - boot application image from memory
3323 bootp - boot image via network using BootP/TFTP protocol
3324 bootz - boot zImage from memory
3325 tftpboot- boot image via network using TFTP protocol
3326 and env variables "ipaddr" and "serverip"
3327 (and eventually "gatewayip")
3328 tftpput - upload a file via network using TFTP protocol
3329 rarpboot- boot image via network using RARP/TFTP protocol
3330 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
3331 loads - load S-Record file over serial line
3332 loadb - load binary file over serial line (kermit mode)
3334 mm - memory modify (auto-incrementing)
3335 nm - memory modify (constant address)
3336 mw - memory write (fill)
3338 cmp - memory compare
3339 crc32 - checksum calculation
3340 i2c - I2C sub-system
3341 sspi - SPI utility commands
3342 base - print or set address offset
3343 printenv- print environment variables
3344 setenv - set environment variables
3345 saveenv - save environment variables to persistent storage
3346 protect - enable or disable FLASH write protection
3347 erase - erase FLASH memory
3348 flinfo - print FLASH memory information
3349 nand - NAND memory operations (see doc/README.nand)
3350 bdinfo - print Board Info structure
3351 iminfo - print header information for application image
3352 coninfo - print console devices and informations
3353 ide - IDE sub-system
3354 loop - infinite loop on address range
3355 loopw - infinite write loop on address range
3356 mtest - simple RAM test
3357 icache - enable or disable instruction cache
3358 dcache - enable or disable data cache
3359 reset - Perform RESET of the CPU
3360 echo - echo args to console
3361 version - print monitor version
3362 help - print online help
3363 ? - alias for 'help'
3366 Monitor Commands - Detailed Description:
3367 ========================================
3371 For now: just type "help <command>".
3374 Environment Variables:
3375 ======================
3377 U-Boot supports user configuration using Environment Variables which
3378 can be made persistent by saving to Flash memory.
3380 Environment Variables are set using "setenv", printed using
3381 "printenv", and saved to Flash using "saveenv". Using "setenv"
3382 without a value can be used to delete a variable from the
3383 environment. As long as you don't save the environment you are
3384 working with an in-memory copy. In case the Flash area containing the
3385 environment is erased by accident, a default environment is provided.
3387 Some configuration options can be set using Environment Variables.
3389 List of environment variables (most likely not complete):
3391 baudrate - see CONFIG_BAUDRATE
3393 bootdelay - see CONFIG_BOOTDELAY
3395 bootcmd - see CONFIG_BOOTCOMMAND
3397 bootargs - Boot arguments when booting an RTOS image
3399 bootfile - Name of the image to load with TFTP
3401 bootm_low - Memory range available for image processing in the bootm
3402 command can be restricted. This variable is given as
3403 a hexadecimal number and defines lowest address allowed
3404 for use by the bootm command. See also "bootm_size"
3405 environment variable. Address defined by "bootm_low" is
3406 also the base of the initial memory mapping for the Linux
3407 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3410 bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3411 This variable is given as a hexadecimal number and it
3412 defines the size of the memory region starting at base
3413 address bootm_low that is accessible by the Linux kernel
3414 during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
3415 as the default value if it is defined, and bootm_size is
3418 bootm_size - Memory range available for image processing in the bootm
3419 command can be restricted. This variable is given as
3420 a hexadecimal number and defines the size of the region
3421 allowed for use by the bootm command. See also "bootm_low"
3422 environment variable.
3424 bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
3426 updatefile - Location of the software update file on a TFTP server, used
3427 by the automatic software update feature. Please refer to
3428 documentation in doc/README.update for more details.
3430 autoload - if set to "no" (any string beginning with 'n'),
3431 "bootp" will just load perform a lookup of the
3432 configuration from the BOOTP server, but not try to
3433 load any image using TFTP
3435 autostart - if set to "yes", an image loaded using the "bootp",
3436 "rarpboot", "tftpboot" or "diskboot" commands will
3437 be automatically started (by internally calling
3440 If set to "no", a standalone image passed to the
3441 "bootm" command will be copied to the load address
3442 (and eventually uncompressed), but NOT be started.
3443 This can be used to load and uncompress arbitrary
3446 fdt_high - if set this restricts the maximum address that the
3447 flattened device tree will be copied into upon boot.
3448 For example, if you have a system with 1 GB memory
3449 at physical address 0x10000000, while Linux kernel
3450 only recognizes the first 704 MB as low memory, you
3451 may need to set fdt_high as 0x3C000000 to have the
3452 device tree blob be copied to the maximum address
3453 of the 704 MB low memory, so that Linux kernel can
3454 access it during the boot procedure.
3456 If this is set to the special value 0xFFFFFFFF then
3457 the fdt will not be copied at all on boot. For this
3458 to work it must reside in writable memory, have
3459 sufficient padding on the end of it for u-boot to
3460 add the information it needs into it, and the memory
3461 must be accessible by the kernel.
3463 fdtcontroladdr- if set this is the address of the control flattened
3464 device tree used by U-Boot when CONFIG_OF_CONTROL is
3467 i2cfast - (PPC405GP|PPC405EP only)
3468 if set to 'y' configures Linux I2C driver for fast
3469 mode (400kHZ). This environment variable is used in
3470 initialization code. So, for changes to be effective
3471 it must be saved and board must be reset.
3473 initrd_high - restrict positioning of initrd images:
3474 If this variable is not set, initrd images will be
3475 copied to the highest possible address in RAM; this
3476 is usually what you want since it allows for
3477 maximum initrd size. If for some reason you want to
3478 make sure that the initrd image is loaded below the
3479 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3480 variable to a value of "no" or "off" or "0".
3481 Alternatively, you can set it to a maximum upper
3482 address to use (U-Boot will still check that it
3483 does not overwrite the U-Boot stack and data).
3485 For instance, when you have a system with 16 MB
3486 RAM, and want to reserve 4 MB from use by Linux,
3487 you can do this by adding "mem=12M" to the value of
3488 the "bootargs" variable. However, now you must make
3489 sure that the initrd image is placed in the first
3490 12 MB as well - this can be done with
3492 setenv initrd_high 00c00000
3494 If you set initrd_high to 0xFFFFFFFF, this is an
3495 indication to U-Boot that all addresses are legal
3496 for the Linux kernel, including addresses in flash
3497 memory. In this case U-Boot will NOT COPY the
3498 ramdisk at all. This may be useful to reduce the
3499 boot time on your system, but requires that this
3500 feature is supported by your Linux kernel.
3502 ipaddr - IP address; needed for tftpboot command
3504 loadaddr - Default load address for commands like "bootp",
3505 "rarpboot", "tftpboot", "loadb" or "diskboot"
3507 loads_echo - see CONFIG_LOADS_ECHO
3509 serverip - TFTP server IP address; needed for tftpboot command
3511 bootretry - see CONFIG_BOOT_RETRY_TIME
3513 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
3515 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
3517 ethprime - controls which interface is used first.
3519 ethact - controls which interface is currently active.
3520 For example you can do the following
3522 => setenv ethact FEC
3523 => ping 192.168.0.1 # traffic sent on FEC
3524 => setenv ethact SCC
3525 => ping 10.0.0.1 # traffic sent on SCC
3527 ethrotate - When set to "no" U-Boot does not go through all
3528 available network interfaces.
3529 It just stays at the currently selected interface.
3531 netretry - When set to "no" each network operation will
3532 either succeed or fail without retrying.
3533 When set to "once" the network operation will
3534 fail when all the available network interfaces
3535 are tried once without success.
3536 Useful on scripts which control the retry operation
3539 npe_ucode - set load address for the NPE microcode
3541 silent_linux - If set then Linux will be told to boot silently, by
3542 changing the console to be empty. If "yes" it will be
3543 made silent. If "no" it will not be made silent. If
3544 unset, then it will be made silent if the U-Boot console
3547 tftpsrcp - If this is set, the value is used for TFTP's
3550 tftpdstp - If this is set, the value is used for TFTP's UDP
3551 destination port instead of the Well Know Port 69.
3553 tftpblocksize - Block size to use for TFTP transfers; if not set,
3554 we use the TFTP server's default block size
3556 tftptimeout - Retransmission timeout for TFTP packets (in milli-
3557 seconds, minimum value is 1000 = 1 second). Defines
3558 when a packet is considered to be lost so it has to
3559 be retransmitted. The default is 5000 = 5 seconds.
3560 Lowering this value may make downloads succeed
3561 faster in networks with high packet loss rates or
3562 with unreliable TFTP servers.
3564 tftptimeoutcountmax - maximum count of TFTP timeouts (no
3565 unit, minimum value = 0). Defines how many timeouts
3566 can happen during a single file transfer before that
3567 transfer is aborted. The default is 10, and 0 means
3568 'no timeouts allowed'. Increasing this value may help
3569 downloads succeed with high packet loss rates, or with
3570 unreliable TFTP servers or client hardware.
3572 vlan - When set to a value < 4095 the traffic over
3573 Ethernet is encapsulated/received over 802.1q
3576 bootpretryperiod - Period during which BOOTP/DHCP sends retries.
3577 Unsigned value, in milliseconds. If not set, the period will
3578 be either the default (28000), or a value based on
3579 CONFIG_NET_RETRY_COUNT, if defined. This value has
3580 precedence over the valu based on CONFIG_NET_RETRY_COUNT.
3582 The following image location variables contain the location of images
3583 used in booting. The "Image" column gives the role of the image and is
3584 not an environment variable name. The other columns are environment
3585 variable names. "File Name" gives the name of the file on a TFTP
3586 server, "RAM Address" gives the location in RAM the image will be
3587 loaded to, and "Flash Location" gives the image's address in NOR
3588 flash or offset in NAND flash.
3590 *Note* - these variables don't have to be defined for all boards, some
3591 boards currently use other variables for these purposes, and some
3592 boards use these variables for other purposes.
3594 Image File Name RAM Address Flash Location
3595 ----- --------- ----------- --------------
3596 u-boot u-boot u-boot_addr_r u-boot_addr
3597 Linux kernel bootfile kernel_addr_r kernel_addr
3598 device tree blob fdtfile fdt_addr_r fdt_addr
3599 ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
3601 The following environment variables may be used and automatically
3602 updated by the network boot commands ("bootp" and "rarpboot"),
3603 depending the information provided by your boot server:
3605 bootfile - see above
3606 dnsip - IP address of your Domain Name Server
3607 dnsip2 - IP address of your secondary Domain Name Server
3608 gatewayip - IP address of the Gateway (Router) to use
3609 hostname - Target hostname
3611 netmask - Subnet Mask
3612 rootpath - Pathname of the root filesystem on the NFS server
3613 serverip - see above
3616 There are two special Environment Variables:
3618 serial# - contains hardware identification information such
3619 as type string and/or serial number
3620 ethaddr - Ethernet address
3622 These variables can be set only once (usually during manufacturing of
3623 the board). U-Boot refuses to delete or overwrite these variables
3624 once they have been set once.
3627 Further special Environment Variables:
3629 ver - Contains the U-Boot version string as printed
3630 with the "version" command. This variable is
3631 readonly (see CONFIG_VERSION_VARIABLE).
3634 Please note that changes to some configuration parameters may take
3635 only effect after the next boot (yes, that's just like Windoze :-).
3638 Callback functions for environment variables:
3639 ---------------------------------------------
3641 For some environment variables, the behavior of u-boot needs to change
3642 when their values are changed. This functionality allows functions to
3643 be associated with arbitrary variables. On creation, overwrite, or
3644 deletion, the callback will provide the opportunity for some side
3645 effect to happen or for the change to be rejected.
3647 The callbacks are named and associated with a function using the
3648 U_BOOT_ENV_CALLBACK macro in your board or driver code.
3650 These callbacks are associated with variables in one of two ways. The
3651 static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
3652 in the board configuration to a string that defines a list of
3653 associations. The list must be in the following format:
3655 entry = variable_name[:callback_name]
3658 If the callback name is not specified, then the callback is deleted.
3659 Spaces are also allowed anywhere in the list.
3661 Callbacks can also be associated by defining the ".callbacks" variable
3662 with the same list format above. Any association in ".callbacks" will
3663 override any association in the static list. You can define
3664 CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
3665 ".callbacks" environment variable in the default or embedded environment.
3667 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3668 regular expression. This allows multiple variables to be connected to
3669 the same callback without explicitly listing them all out.
3671 The signature of the callback functions is:
3673 int callback(const char *name, const char *value, enum env_op op, int flags)
3675 * name - changed environment variable
3676 * value - new value of the environment variable
3677 * op - operation (create, overwrite, or delete)
3678 * flags - attributes of the environment variable change, see flags H_* in
3681 The return value is 0 if the variable change is accepted and 1 otherwise.
3683 Command Line Parsing:
3684 =====================
3686 There are two different command line parsers available with U-Boot:
3687 the old "simple" one, and the much more powerful "hush" shell:
3689 Old, simple command line parser:
3690 --------------------------------
3692 - supports environment variables (through setenv / saveenv commands)
3693 - several commands on one line, separated by ';'
3694 - variable substitution using "... ${name} ..." syntax
3695 - special characters ('$', ';') can be escaped by prefixing with '\',
3697 setenv bootcmd bootm \${address}
3698 - You can also escape text by enclosing in single apostrophes, for example:
3699 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3704 - similar to Bourne shell, with control structures like
3705 if...then...else...fi, for...do...done; while...do...done,
3706 until...do...done, ...
3707 - supports environment ("global") variables (through setenv / saveenv
3708 commands) and local shell variables (through standard shell syntax
3709 "name=value"); only environment variables can be used with "run"
3715 (1) If a command line (or an environment variable executed by a "run"
3716 command) contains several commands separated by semicolon, and
3717 one of these commands fails, then the remaining commands will be
3720 (2) If you execute several variables with one call to run (i. e.
3721 calling run with a list of variables as arguments), any failing
3722 command will cause "run" to terminate, i. e. the remaining
3723 variables are not executed.
3725 Note for Redundant Ethernet Interfaces:
3726 =======================================
3728 Some boards come with redundant Ethernet interfaces; U-Boot supports
3729 such configurations and is capable of automatic selection of a
3730 "working" interface when needed. MAC assignment works as follows:
3732 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3733 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3734 "eth1addr" (=>eth1), "eth2addr", ...
3736 If the network interface stores some valid MAC address (for instance
3737 in SROM), this is used as default address if there is NO correspon-
3738 ding setting in the environment; if the corresponding environment
3739 variable is set, this overrides the settings in the card; that means:
3741 o If the SROM has a valid MAC address, and there is no address in the
3742 environment, the SROM's address is used.
3744 o If there is no valid address in the SROM, and a definition in the
3745 environment exists, then the value from the environment variable is
3748 o If both the SROM and the environment contain a MAC address, and
3749 both addresses are the same, this MAC address is used.
3751 o If both the SROM and the environment contain a MAC address, and the
3752 addresses differ, the value from the environment is used and a
3755 o If neither SROM nor the environment contain a MAC address, an error
3756 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
3757 a random, locally-assigned MAC is used.
3759 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3760 will be programmed into hardware as part of the initialization process. This
3761 may be skipped by setting the appropriate 'ethmacskip' environment variable.
3762 The naming convention is as follows:
3763 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3768 U-Boot is capable of booting (and performing other auxiliary operations on)
3769 images in two formats:
3771 New uImage format (FIT)
3772 -----------------------
3774 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3775 to Flattened Device Tree). It allows the use of images with multiple
3776 components (several kernels, ramdisks, etc.), with contents protected by
3777 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3783 Old image format is based on binary files which can be basically anything,
3784 preceded by a special header; see the definitions in include/image.h for
3785 details; basically, the header defines the following image properties:
3787 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3788 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3789 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3790 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3792 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
3793 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3794 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3795 * Compression Type (uncompressed, gzip, bzip2)
3801 The header is marked by a special Magic Number, and both the header
3802 and the data portions of the image are secured against corruption by
3809 Although U-Boot should support any OS or standalone application
3810 easily, the main focus has always been on Linux during the design of
3813 U-Boot includes many features that so far have been part of some
3814 special "boot loader" code within the Linux kernel. Also, any
3815 "initrd" images to be used are no longer part of one big Linux image;
3816 instead, kernel and "initrd" are separate images. This implementation
3817 serves several purposes:
3819 - the same features can be used for other OS or standalone
3820 applications (for instance: using compressed images to reduce the
3821 Flash memory footprint)
3823 - it becomes much easier to port new Linux kernel versions because
3824 lots of low-level, hardware dependent stuff are done by U-Boot
3826 - the same Linux kernel image can now be used with different "initrd"
3827 images; of course this also means that different kernel images can
3828 be run with the same "initrd". This makes testing easier (you don't
3829 have to build a new "zImage.initrd" Linux image when you just
3830 change a file in your "initrd"). Also, a field-upgrade of the
3831 software is easier now.
3837 Porting Linux to U-Boot based systems:
3838 ---------------------------------------
3840 U-Boot cannot save you from doing all the necessary modifications to
3841 configure the Linux device drivers for use with your target hardware
3842 (no, we don't intend to provide a full virtual machine interface to
3845 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3847 Just make sure your machine specific header file (for instance
3848 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3849 Information structure as we define in include/asm-<arch>/u-boot.h,
3850 and make sure that your definition of IMAP_ADDR uses the same value
3851 as your U-Boot configuration in CONFIG_SYS_IMMR.
3853 Note that U-Boot now has a driver model, a unified model for drivers.
3854 If you are adding a new driver, plumb it into driver model. If there
3855 is no uclass available, you are encouraged to create one. See
3859 Configuring the Linux kernel:
3860 -----------------------------
3862 No specific requirements for U-Boot. Make sure you have some root
3863 device (initial ramdisk, NFS) for your target system.
3866 Building a Linux Image:
3867 -----------------------
3869 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3870 not used. If you use recent kernel source, a new build target
3871 "uImage" will exist which automatically builds an image usable by
3872 U-Boot. Most older kernels also have support for a "pImage" target,
3873 which was introduced for our predecessor project PPCBoot and uses a
3874 100% compatible format.
3878 make TQM850L_defconfig
3883 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3884 encapsulate a compressed Linux kernel image with header information,
3885 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3887 * build a standard "vmlinux" kernel image (in ELF binary format):
3889 * convert the kernel into a raw binary image:
3891 ${CROSS_COMPILE}-objcopy -O binary \
3892 -R .note -R .comment \
3893 -S vmlinux linux.bin
3895 * compress the binary image:
3899 * package compressed binary image for U-Boot:
3901 mkimage -A ppc -O linux -T kernel -C gzip \
3902 -a 0 -e 0 -n "Linux Kernel Image" \
3903 -d linux.bin.gz uImage
3906 The "mkimage" tool can also be used to create ramdisk images for use
3907 with U-Boot, either separated from the Linux kernel image, or
3908 combined into one file. "mkimage" encapsulates the images with a 64
3909 byte header containing information about target architecture,
3910 operating system, image type, compression method, entry points, time
3911 stamp, CRC32 checksums, etc.
3913 "mkimage" can be called in two ways: to verify existing images and
3914 print the header information, or to build new images.
3916 In the first form (with "-l" option) mkimage lists the information
3917 contained in the header of an existing U-Boot image; this includes
3918 checksum verification:
3920 tools/mkimage -l image
3921 -l ==> list image header information
3923 The second form (with "-d" option) is used to build a U-Boot image
3924 from a "data file" which is used as image payload:
3926 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3927 -n name -d data_file image
3928 -A ==> set architecture to 'arch'
3929 -O ==> set operating system to 'os'
3930 -T ==> set image type to 'type'
3931 -C ==> set compression type 'comp'
3932 -a ==> set load address to 'addr' (hex)
3933 -e ==> set entry point to 'ep' (hex)
3934 -n ==> set image name to 'name'
3935 -d ==> use image data from 'datafile'
3937 Right now, all Linux kernels for PowerPC systems use the same load
3938 address (0x00000000), but the entry point address depends on the
3941 - 2.2.x kernels have the entry point at 0x0000000C,
3942 - 2.3.x and later kernels have the entry point at 0x00000000.
3944 So a typical call to build a U-Boot image would read:
3946 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3947 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3948 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3949 > examples/uImage.TQM850L
3950 Image Name: 2.4.4 kernel for TQM850L
3951 Created: Wed Jul 19 02:34:59 2000
3952 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3953 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3954 Load Address: 0x00000000
3955 Entry Point: 0x00000000
3957 To verify the contents of the image (or check for corruption):
3959 -> tools/mkimage -l examples/uImage.TQM850L
3960 Image Name: 2.4.4 kernel for TQM850L
3961 Created: Wed Jul 19 02:34:59 2000
3962 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3963 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3964 Load Address: 0x00000000
3965 Entry Point: 0x00000000
3967 NOTE: for embedded systems where boot time is critical you can trade
3968 speed for memory and install an UNCOMPRESSED image instead: this
3969 needs more space in Flash, but boots much faster since it does not
3970 need to be uncompressed:
3972 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3973 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3974 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3975 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3976 > examples/uImage.TQM850L-uncompressed
3977 Image Name: 2.4.4 kernel for TQM850L
3978 Created: Wed Jul 19 02:34:59 2000
3979 Image Type: PowerPC Linux Kernel Image (uncompressed)
3980 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3981 Load Address: 0x00000000
3982 Entry Point: 0x00000000
3985 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3986 when your kernel is intended to use an initial ramdisk:
3988 -> tools/mkimage -n 'Simple Ramdisk Image' \
3989 > -A ppc -O linux -T ramdisk -C gzip \
3990 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3991 Image Name: Simple Ramdisk Image
3992 Created: Wed Jan 12 14:01:50 2000
3993 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3994 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3995 Load Address: 0x00000000
3996 Entry Point: 0x00000000
3998 The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
3999 option performs the converse operation of the mkimage's second form (the "-d"
4000 option). Given an image built by mkimage, the dumpimage extracts a "data file"
4003 tools/dumpimage -i image -T type -p position data_file
4004 -i ==> extract from the 'image' a specific 'data_file'
4005 -T ==> set image type to 'type'
4006 -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
4009 Installing a Linux Image:
4010 -------------------------
4012 To downloading a U-Boot image over the serial (console) interface,
4013 you must convert the image to S-Record format:
4015 objcopy -I binary -O srec examples/image examples/image.srec
4017 The 'objcopy' does not understand the information in the U-Boot
4018 image header, so the resulting S-Record file will be relative to
4019 address 0x00000000. To load it to a given address, you need to
4020 specify the target address as 'offset' parameter with the 'loads'
4023 Example: install the image to address 0x40100000 (which on the
4024 TQM8xxL is in the first Flash bank):
4026 => erase 40100000 401FFFFF
4032 ## Ready for S-Record download ...
4033 ~>examples/image.srec
4034 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4036 15989 15990 15991 15992
4037 [file transfer complete]
4039 ## Start Addr = 0x00000000
4042 You can check the success of the download using the 'iminfo' command;
4043 this includes a checksum verification so you can be sure no data
4044 corruption happened:
4048 ## Checking Image at 40100000 ...
4049 Image Name: 2.2.13 for initrd on TQM850L
4050 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4051 Data Size: 335725 Bytes = 327 kB = 0 MB
4052 Load Address: 00000000
4053 Entry Point: 0000000c
4054 Verifying Checksum ... OK
4060 The "bootm" command is used to boot an application that is stored in
4061 memory (RAM or Flash). In case of a Linux kernel image, the contents
4062 of the "bootargs" environment variable is passed to the kernel as
4063 parameters. You can check and modify this variable using the
4064 "printenv" and "setenv" commands:
4067 => printenv bootargs
4068 bootargs=root=/dev/ram
4070 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4072 => printenv bootargs
4073 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4076 ## Booting Linux kernel at 40020000 ...
4077 Image Name: 2.2.13 for NFS on TQM850L
4078 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4079 Data Size: 381681 Bytes = 372 kB = 0 MB
4080 Load Address: 00000000
4081 Entry Point: 0000000c
4082 Verifying Checksum ... OK
4083 Uncompressing Kernel Image ... OK
4084 Linux version 2.2.13 (
[email protected]) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
4085 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4086 time_init: decrementer frequency = 187500000/60
4087 Calibrating delay loop... 49.77 BogoMIPS
4088 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4091 If you want to boot a Linux kernel with initial RAM disk, you pass
4092 the memory addresses of both the kernel and the initrd image (PPBCOOT
4093 format!) to the "bootm" command:
4095 => imi 40100000 40200000
4097 ## Checking Image at 40100000 ...
4098 Image Name: 2.2.13 for initrd on TQM850L
4099 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4100 Data Size: 335725 Bytes = 327 kB = 0 MB
4101 Load Address: 00000000
4102 Entry Point: 0000000c
4103 Verifying Checksum ... OK
4105 ## Checking Image at 40200000 ...
4106 Image Name: Simple Ramdisk Image
4107 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4108 Data Size: 566530 Bytes = 553 kB = 0 MB
4109 Load Address: 00000000
4110 Entry Point: 00000000
4111 Verifying Checksum ... OK
4113 => bootm 40100000 40200000
4114 ## Booting Linux kernel at 40100000 ...
4115 Image Name: 2.2.13 for initrd on TQM850L
4116 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4117 Data Size: 335725 Bytes = 327 kB = 0 MB
4118 Load Address: 00000000
4119 Entry Point: 0000000c
4120 Verifying Checksum ... OK
4121 Uncompressing Kernel Image ... OK
4122 ## Loading RAMDisk Image at 40200000 ...
4123 Image Name: Simple Ramdisk Image
4124 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
4125 Data Size: 566530 Bytes = 553 kB = 0 MB
4126 Load Address: 00000000
4127 Entry Point: 00000000
4128 Verifying Checksum ... OK
4129 Loading Ramdisk ... OK
4130 Linux version 2.2.13 (
[email protected]) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
4131 Boot arguments: root=/dev/ram
4132 time_init: decrementer frequency = 187500000/60
4133 Calibrating delay loop... 49.77 BogoMIPS
4135 RAMDISK: Compressed image found at block 0
4136 VFS: Mounted root (ext2 filesystem).
4140 Boot Linux and pass a flat device tree:
4143 First, U-Boot must be compiled with the appropriate defines. See the section
4144 titled "Linux Kernel Interface" above for a more in depth explanation. The
4145 following is an example of how to start a kernel and pass an updated
4151 oft=oftrees/mpc8540ads.dtb
4152 => tftp $oftaddr $oft
4153 Speed: 1000, full duplex
4155 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4156 Filename 'oftrees/mpc8540ads.dtb'.
4157 Load address: 0x300000
4160 Bytes transferred = 4106 (100a hex)
4161 => tftp $loadaddr $bootfile
4162 Speed: 1000, full duplex
4164 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4166 Load address: 0x200000
4167 Loading:############
4169 Bytes transferred = 1029407 (fb51f hex)
4174 => bootm $loadaddr - $oftaddr
4175 ## Booting image at 00200000 ...
4176 Image Name: Linux-2.6.17-dirty
4177 Image Type: PowerPC Linux Kernel Image (gzip compressed)
4178 Data Size: 1029343 Bytes = 1005.2 kB
4179 Load Address: 00000000
4180 Entry Point: 00000000
4181 Verifying Checksum ... OK
4182 Uncompressing Kernel Image ... OK
4183 Booting using flat device tree at 0x300000
4184 Using MPC85xx ADS machine description
4185 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4189 More About U-Boot Image Types:
4190 ------------------------------
4192 U-Boot supports the following image types:
4194 "Standalone Programs" are directly runnable in the environment
4195 provided by U-Boot; it is expected that (if they behave
4196 well) you can continue to work in U-Boot after return from
4197 the Standalone Program.
4198 "OS Kernel Images" are usually images of some Embedded OS which
4199 will take over control completely. Usually these programs
4200 will install their own set of exception handlers, device
4201 drivers, set up the MMU, etc. - this means, that you cannot
4202 expect to re-enter U-Boot except by resetting the CPU.
4203 "RAMDisk Images" are more or less just data blocks, and their
4204 parameters (address, size) are passed to an OS kernel that is
4206 "Multi-File Images" contain several images, typically an OS
4207 (Linux) kernel image and one or more data images like
4208 RAMDisks. This construct is useful for instance when you want
4209 to boot over the network using BOOTP etc., where the boot
4210 server provides just a single image file, but you want to get
4211 for instance an OS kernel and a RAMDisk image.
4213 "Multi-File Images" start with a list of image sizes, each
4214 image size (in bytes) specified by an "uint32_t" in network
4215 byte order. This list is terminated by an "(uint32_t)0".
4216 Immediately after the terminating 0 follow the images, one by
4217 one, all aligned on "uint32_t" boundaries (size rounded up to
4218 a multiple of 4 bytes).
4220 "Firmware Images" are binary images containing firmware (like
4221 U-Boot or FPGA images) which usually will be programmed to
4224 "Script files" are command sequences that will be executed by
4225 U-Boot's command interpreter; this feature is especially
4226 useful when you configure U-Boot to use a real shell (hush)
4227 as command interpreter.
4229 Booting the Linux zImage:
4230 -------------------------
4232 On some platforms, it's possible to boot Linux zImage. This is done
4233 using the "bootz" command. The syntax of "bootz" command is the same
4234 as the syntax of "bootm" command.
4236 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
4237 kernel with raw initrd images. The syntax is slightly different, the
4238 address of the initrd must be augmented by it's size, in the following
4239 format: "<initrd addres>:<initrd size>".
4245 One of the features of U-Boot is that you can dynamically load and
4246 run "standalone" applications, which can use some resources of
4247 U-Boot like console I/O functions or interrupt services.
4249 Two simple examples are included with the sources:
4254 'examples/hello_world.c' contains a small "Hello World" Demo
4255 application; it is automatically compiled when you build U-Boot.
4256 It's configured to run at address 0x00040004, so you can play with it
4260 ## Ready for S-Record download ...
4261 ~>examples/hello_world.srec
4262 1 2 3 4 5 6 7 8 9 10 11 ...
4263 [file transfer complete]
4265 ## Start Addr = 0x00040004
4267 => go 40004 Hello World! This is a test.
4268 ## Starting application at 0x00040004 ...
4279 Hit any key to exit ...
4281 ## Application terminated, rc = 0x0
4283 Another example, which demonstrates how to register a CPM interrupt
4284 handler with the U-Boot code, can be found in 'examples/timer.c'.
4285 Here, a CPM timer is set up to generate an interrupt every second.
4286 The interrupt service routine is trivial, just printing a '.'
4287 character, but this is just a demo program. The application can be
4288 controlled by the following keys:
4290 ? - print current values og the CPM Timer registers
4291 b - enable interrupts and start timer
4292 e - stop timer and disable interrupts
4293 q - quit application
4296 ## Ready for S-Record download ...
4297 ~>examples/timer.srec
4298 1 2 3 4 5 6 7 8 9 10 11 ...
4299 [file transfer complete]
4301 ## Start Addr = 0x00040004
4304 ## Starting application at 0x00040004 ...
4307 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4310 [q, b, e, ?] Set interval 1000000 us
4313 [q, b, e, ?] ........
4314 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4317 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4320 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4323 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4325 [q, b, e, ?] ...Stopping timer
4327 [q, b, e, ?] ## Application terminated, rc = 0x0
4333 Over time, many people have reported problems when trying to use the
4334 "minicom" terminal emulation program for serial download. I (wd)
4335 consider minicom to be broken, and recommend not to use it. Under
4336 Unix, I recommend to use C-Kermit for general purpose use (and
4337 especially for kermit binary protocol download ("loadb" command), and
4338 use "cu" for S-Record download ("loads" command). See
4339 http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
4340 for help with kermit.
4343 Nevertheless, if you absolutely want to use it try adding this
4344 configuration to your "File transfer protocols" section:
4346 Name Program Name U/D FullScr IO-Red. Multi
4347 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
4348 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
4354 Starting at version 0.9.2, U-Boot supports NetBSD both as host
4355 (build U-Boot) and target system (boots NetBSD/mpc8xx).
4357 Building requires a cross environment; it is known to work on
4358 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4359 need gmake since the Makefiles are not compatible with BSD make).
4360 Note that the cross-powerpc package does not install include files;
4361 attempting to build U-Boot will fail because <machine/ansi.h> is
4362 missing. This file has to be installed and patched manually:
4364 # cd /usr/pkg/cross/powerpc-netbsd/include
4366 # ln -s powerpc machine
4367 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4368 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
4370 Native builds *don't* work due to incompatibilities between native
4371 and U-Boot include files.
4373 Booting assumes that (the first part of) the image booted is a
4374 stage-2 loader which in turn loads and then invokes the kernel
4375 proper. Loader sources will eventually appear in the NetBSD source
4376 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4377 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4380 Implementation Internals:
4381 =========================
4383 The following is not intended to be a complete description of every
4384 implementation detail. However, it should help to understand the
4385 inner workings of U-Boot and make it easier to port it to custom
4389 Initial Stack, Global Data:
4390 ---------------------------
4392 The implementation of U-Boot is complicated by the fact that U-Boot
4393 starts running out of ROM (flash memory), usually without access to
4394 system RAM (because the memory controller is not initialized yet).
4395 This means that we don't have writable Data or BSS segments, and BSS
4396 is not initialized as zero. To be able to get a C environment working
4397 at all, we have to allocate at least a minimal stack. Implementation
4398 options for this are defined and restricted by the CPU used: Some CPU
4399 models provide on-chip memory (like the IMMR area on MPC8xx and
4400 MPC826x processors), on others (parts of) the data cache can be
4401 locked as (mis-) used as memory, etc.
4403 Chris Hallinan posted a good summary of these issues to the
4404 U-Boot mailing list:
4406 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4408 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4411 Correct me if I'm wrong, folks, but the way I understand it
4412 is this: Using DCACHE as initial RAM for Stack, etc, does not
4413 require any physical RAM backing up the cache. The cleverness
4414 is that the cache is being used as a temporary supply of
4415 necessary storage before the SDRAM controller is setup. It's
4416 beyond the scope of this list to explain the details, but you
4417 can see how this works by studying the cache architecture and
4418 operation in the architecture and processor-specific manuals.
4420 OCM is On Chip Memory, which I believe the 405GP has 4K. It
4421 is another option for the system designer to use as an
4422 initial stack/RAM area prior to SDRAM being available. Either
4423 option should work for you. Using CS 4 should be fine if your
4424 board designers haven't used it for something that would
4425 cause you grief during the initial boot! It is frequently not
4428 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4429 with your processor/board/system design. The default value
4430 you will find in any recent u-boot distribution in
4431 walnut.h should work for you. I'd set it to a value larger
4432 than your SDRAM module. If you have a 64MB SDRAM module, set
4433 it above 400_0000. Just make sure your board has no resources
4434 that are supposed to respond to that address! That code in
4435 start.S has been around a while and should work as is when
4436 you get the config right.
4441 It is essential to remember this, since it has some impact on the C
4442 code for the initialization procedures:
4444 * Initialized global data (data segment) is read-only. Do not attempt
4447 * Do not use any uninitialized global data (or implicitly initialized
4448 as zero data - BSS segment) at all - this is undefined, initiali-
4449 zation is performed later (when relocating to RAM).
4451 * Stack space is very limited. Avoid big data buffers or things like
4454 Having only the stack as writable memory limits means we cannot use
4455 normal global data to share information between the code. But it
4456 turned out that the implementation of U-Boot can be greatly
4457 simplified by making a global data structure (gd_t) available to all
4458 functions. We could pass a pointer to this data as argument to _all_
4459 functions, but this would bloat the code. Instead we use a feature of
4460 the GCC compiler (Global Register Variables) to share the data: we
4461 place a pointer (gd) to the global data into a register which we
4462 reserve for this purpose.
4464 When choosing a register for such a purpose we are restricted by the
4465 relevant (E)ABI specifications for the current architecture, and by
4466 GCC's implementation.
4468 For PowerPC, the following registers have specific use:
4470 R2: reserved for system use
4471 R3-R4: parameter passing and return values
4472 R5-R10: parameter passing
4473 R13: small data area pointer
4477 (U-Boot also uses R12 as internal GOT pointer. r12
4478 is a volatile register so r12 needs to be reset when
4479 going back and forth between asm and C)
4481 ==> U-Boot will use R2 to hold a pointer to the global data
4483 Note: on PPC, we could use a static initializer (since the
4484 address of the global data structure is known at compile time),
4485 but it turned out that reserving a register results in somewhat
4486 smaller code - although the code savings are not that big (on
4487 average for all boards 752 bytes for the whole U-Boot image,
4488 624 text + 127 data).
4490 On ARM, the following registers are used:
4492 R0: function argument word/integer result
4493 R1-R3: function argument word
4494 R9: platform specific
4495 R10: stack limit (used only if stack checking is enabled)
4496 R11: argument (frame) pointer
4497 R12: temporary workspace
4500 R15: program counter
4502 ==> U-Boot will use R9 to hold a pointer to the global data
4504 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
4506 On Nios II, the ABI is documented here:
4507 http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4509 ==> U-Boot will use gp to hold a pointer to the global data
4511 Note: on Nios II, we give "-G0" option to gcc and don't use gp
4512 to access small data sections, so gp is free.
4514 On NDS32, the following registers are used:
4516 R0-R1: argument/return
4518 R15: temporary register for assembler
4519 R16: trampoline register
4520 R28: frame pointer (FP)
4521 R29: global pointer (GP)
4522 R30: link register (LP)
4523 R31: stack pointer (SP)
4524 PC: program counter (PC)
4526 ==> U-Boot will use R10 to hold a pointer to the global data
4528 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4529 or current versions of GCC may "optimize" the code too much.
4531 On RISC-V, the following registers are used:
4533 x0: hard-wired zero (zero)
4534 x1: return address (ra)
4535 x2: stack pointer (sp)
4536 x3: global pointer (gp)
4537 x4: thread pointer (tp)
4538 x5: link register (t0)
4539 x8: frame pointer (fp)
4540 x10-x11: arguments/return values (a0-1)
4541 x12-x17: arguments (a2-7)
4542 x28-31: temporaries (t3-6)
4543 pc: program counter (pc)
4545 ==> U-Boot will use gp to hold a pointer to the global data
4550 U-Boot runs in system state and uses physical addresses, i.e. the
4551 MMU is not used either for address mapping nor for memory protection.
4553 The available memory is mapped to fixed addresses using the memory
4554 controller. In this process, a contiguous block is formed for each
4555 memory type (Flash, SDRAM, SRAM), even when it consists of several
4556 physical memory banks.
4558 U-Boot is installed in the first 128 kB of the first Flash bank (on
4559 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4560 booting and sizing and initializing DRAM, the code relocates itself
4561 to the upper end of DRAM. Immediately below the U-Boot code some
4562 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4563 configuration setting]. Below that, a structure with global Board
4564 Info data is placed, followed by the stack (growing downward).
4566 Additionally, some exception handler code is copied to the low 8 kB
4567 of DRAM (0x00000000 ... 0x00001FFF).
4569 So a typical memory configuration with 16 MB of DRAM could look like
4572 0x0000 0000 Exception Vector code
4575 0x0000 2000 Free for Application Use
4581 0x00FB FF20 Monitor Stack (Growing downward)
4582 0x00FB FFAC Board Info Data and permanent copy of global data
4583 0x00FC 0000 Malloc Arena
4586 0x00FE 0000 RAM Copy of Monitor Code
4587 ... eventually: LCD or video framebuffer
4588 ... eventually: pRAM (Protected RAM - unchanged by reset)
4589 0x00FF FFFF [End of RAM]
4592 System Initialization:
4593 ----------------------
4595 In the reset configuration, U-Boot starts at the reset entry point
4596 (on most PowerPC systems at address 0x00000100). Because of the reset
4597 configuration for CS0# this is a mirror of the on board Flash memory.
4598 To be able to re-map memory U-Boot then jumps to its link address.
4599 To be able to implement the initialization code in C, a (small!)
4600 initial stack is set up in the internal Dual Ported RAM (in case CPUs
4601 which provide such a feature like), or in a locked part of the data
4602 cache. After that, U-Boot initializes the CPU core, the caches and
4605 Next, all (potentially) available memory banks are mapped using a
4606 preliminary mapping. For example, we put them on 512 MB boundaries
4607 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4608 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4609 programmed for SDRAM access. Using the temporary configuration, a
4610 simple memory test is run that determines the size of the SDRAM
4613 When there is more than one SDRAM bank, and the banks are of
4614 different size, the largest is mapped first. For equal size, the first
4615 bank (CS2#) is mapped first. The first mapping is always for address
4616 0x00000000, with any additional banks following immediately to create
4617 contiguous memory starting from 0.
4619 Then, the monitor installs itself at the upper end of the SDRAM area
4620 and allocates memory for use by malloc() and for the global Board
4621 Info data; also, the exception vector code is copied to the low RAM
4622 pages, and the final stack is set up.
4624 Only after this relocation will you have a "normal" C environment;
4625 until that you are restricted in several ways, mostly because you are
4626 running from ROM, and because the code will have to be relocated to a
4630 U-Boot Porting Guide:
4631 ----------------------
4633 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4637 int main(int argc, char *argv[])
4639 sighandler_t no_more_time;
4641 signal(SIGALRM, no_more_time);
4642 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4644 if (available_money > available_manpower) {
4645 Pay consultant to port U-Boot;
4649 Download latest U-Boot source;
4651 Subscribe to u-boot mailing list;
4654 email("Hi, I am new to U-Boot, how do I get started?");
4657 Read the README file in the top level directory;
4658 Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4659 Read applicable doc/*.README;
4660 Read the source, Luke;
4661 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
4664 if (available_money > toLocalCurrency ($2500))
4667 Add a lot of aggravation and time;
4669 if (a similar board exists) { /* hopefully... */
4670 cp -a board/<similar> board/<myboard>
4671 cp include/configs/<similar>.h include/configs/<myboard>.h
4673 Create your own board support subdirectory;
4674 Create your own board include/configs/<myboard>.h file;
4676 Edit new board/<myboard> files
4677 Edit new include/configs/<myboard>.h
4682 Add / modify source code;
4686 email("Hi, I am having problems...");
4688 Send patch file to the U-Boot email list;
4689 if (reasonable critiques)
4690 Incorporate improvements from email list code review;
4692 Defend code as written;
4698 void no_more_time (int sig)
4707 All contributions to U-Boot should conform to the Linux kernel
4708 coding style; see the kernel coding style guide at
4709 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
4710 script "scripts/Lindent" in your Linux kernel source directory.
4712 Source files originating from a different project (for example the
4713 MTD subsystem) are generally exempt from these guidelines and are not
4714 reformatted to ease subsequent migration to newer versions of those
4717 Please note that U-Boot is implemented in C (and to some small parts in
4718 Assembler); no C++ is used, so please do not use C++ style comments (//)
4721 Please also stick to the following formatting rules:
4722 - remove any trailing white space
4723 - use TAB characters for indentation and vertical alignment, not spaces
4724 - make sure NOT to use DOS '\r\n' line feeds
4725 - do not add more than 2 consecutive empty lines to source files
4726 - do not add trailing empty lines to source files
4728 Submissions which do not conform to the standards may be returned
4729 with a request to reformat the changes.
4735 Since the number of patches for U-Boot is growing, we need to
4736 establish some rules. Submissions which do not conform to these rules
4737 may be rejected, even when they contain important and valuable stuff.
4739 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4742 see https://lists.denx.de/listinfo/u-boot
4744 When you send a patch, please include the following information with
4747 * For bug fixes: a description of the bug and how your patch fixes
4748 this bug. Please try to include a way of demonstrating that the
4749 patch actually fixes something.
4751 * For new features: a description of the feature and your
4754 * A CHANGELOG entry as plaintext (separate from the patch)
4756 * For major contributions, add a MAINTAINERS file with your
4757 information and associated file and directory references.
4759 * When you add support for a new board, don't forget to add a
4760 maintainer e-mail address to the boards.cfg file, too.
4762 * If your patch adds new configuration options, don't forget to
4763 document these in the README file.
4765 * The patch itself. If you are using git (which is *strongly*
4766 recommended) you can easily generate the patch using the
4767 "git format-patch". If you then use "git send-email" to send it to
4768 the U-Boot mailing list, you will avoid most of the common problems
4769 with some other mail clients.
4771 If you cannot use git, use "diff -purN OLD NEW". If your version of
4772 diff does not support these options, then get the latest version of
4775 The current directory when running this command shall be the parent
4776 directory of the U-Boot source tree (i. e. please make sure that
4777 your patch includes sufficient directory information for the
4780 We prefer patches as plain text. MIME attachments are discouraged,
4781 and compressed attachments must not be used.
4783 * If one logical set of modifications affects or creates several
4784 files, all these changes shall be submitted in a SINGLE patch file.
4786 * Changesets that contain different, unrelated modifications shall be
4787 submitted as SEPARATE patches, one patch per changeset.
4792 * Before sending the patch, run the buildman script on your patched
4793 source tree and make sure that no errors or warnings are reported
4794 for any of the boards.
4796 * Keep your modifications to the necessary minimum: A patch
4797 containing several unrelated changes or arbitrary reformats will be
4798 returned with a request to re-formatting / split it.
4800 * If you modify existing code, make sure that your new code does not
4801 add to the memory footprint of the code ;-) Small is beautiful!
4802 When adding new features, these should compile conditionally only
4803 (using #ifdef), and the resulting code with the new feature
4804 disabled must not need more memory than the old code without your
4807 * Remember that there is a size limit of 100 kB per message on the
4808 u-boot mailing list. Bigger patches will be moderated. If they are
4809 reasonable and not too big, they will be acknowledged. But patches
4810 bigger than the size limit should be avoided.
projects / J-u-boot.git / blob