1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /boot Support for images and booting
148 /cmd U-Boot commands functions
149 /common Misc architecture-independent functions
150 /configs Board default configuration files
151 /disk Code for disk drive partition handling
152 /doc Documentation (a mix of ReST and READMEs)
153 /drivers Device drivers
154 /dts Makefile for building internal U-Boot fdt.
155 /env Environment support
156 /examples Example code for standalone applications, etc.
157 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
158 /include Header Files
159 /lib Library routines generic to all architectures
160 /Licenses Various license files
162 /post Power On Self Test
163 /scripts Various build scripts and Makefiles
164 /test Various unit test files
165 /tools Tools to build and sign FIT images, etc.
167 Software Configuration:
168 =======================
170 Configuration is usually done using C preprocessor defines; the
171 rationale behind that is to avoid dead code whenever possible.
173 There are two classes of configuration variables:
175 * Configuration _OPTIONS_:
176 These are selectable by the user and have names beginning with
179 * Configuration _SETTINGS_:
180 These depend on the hardware etc. and should not be meddled with if
181 you don't know what you're doing; they have names beginning with
184 Previously, all configuration was done by hand, which involved creating
185 symbolic links and editing configuration files manually. More recently,
186 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
187 allowing you to use the "make menuconfig" command to configure your
191 Selection of Processor Architecture and Board Type:
192 ---------------------------------------------------
194 For all supported boards there are ready-to-use default
195 configurations available; just type "make <board_name>_defconfig".
197 Example: For a TQM823L module type:
200 make TQM823L_defconfig
202 Note: If you're looking for the default configuration file for a board
203 you're sure used to be there but is now missing, check the file
204 doc/README.scrapyard for a list of no longer supported boards.
209 U-Boot can be built natively to run on a Linux host using the 'sandbox'
210 board. This allows feature development which is not board- or architecture-
211 specific to be undertaken on a native platform. The sandbox is also used to
212 run some of U-Boot's tests.
214 See doc/arch/sandbox.rst for more details.
217 Board Initialisation Flow:
218 --------------------------
220 This is the intended start-up flow for boards. This should apply for both
221 SPL and U-Boot proper (i.e. they both follow the same rules).
223 Note: "SPL" stands for "Secondary Program Loader," which is explained in
224 more detail later in this file.
226 At present, SPL mostly uses a separate code path, but the function names
227 and roles of each function are the same. Some boards or architectures
228 may not conform to this. At least most ARM boards which use
229 CONFIG_SPL_FRAMEWORK conform to this.
231 Execution typically starts with an architecture-specific (and possibly
232 CPU-specific) start.S file, such as:
234 - arch/arm/cpu/armv7/start.S
235 - arch/powerpc/cpu/mpc83xx/start.S
236 - arch/mips/cpu/start.S
238 and so on. From there, three functions are called; the purpose and
239 limitations of each of these functions are described below.
242 - purpose: essential init to permit execution to reach board_init_f()
243 - no global_data or BSS
244 - there is no stack (ARMv7 may have one but it will soon be removed)
245 - must not set up SDRAM or use console
246 - must only do the bare minimum to allow execution to continue to
248 - this is almost never needed
249 - return normally from this function
252 - purpose: set up the machine ready for running board_init_r():
253 i.e. SDRAM and serial UART
254 - global_data is available
256 - BSS is not available, so you cannot use global/static variables,
257 only stack variables and global_data
259 Non-SPL-specific notes:
260 - dram_init() is called to set up DRAM. If already done in SPL this
264 - you can override the entire board_init_f() function with your own
266 - preloader_console_init() can be called here in extremis
267 - should set up SDRAM, and anything needed to make the UART work
268 - there is no need to clear BSS, it will be done by crt0.S
269 - for specific scenarios on certain architectures an early BSS *can*
270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
271 of BSS prior to entering board_init_f()) but doing so is discouraged.
272 Instead it is strongly recommended to architect any code changes
273 or additions such to not depend on the availability of BSS during
274 board_init_f() as indicated in other sections of this README to
275 maintain compatibility and consistency across the entire code base.
276 - must return normally from this function (don't call board_init_r()
279 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
280 this point the stack and global_data are relocated to below
281 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
285 - purpose: main execution, common code
286 - global_data is available
288 - BSS is available, all static/global variables can be used
289 - execution eventually continues to main_loop()
291 Non-SPL-specific notes:
292 - U-Boot is relocated to the top of memory and is now running from
296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
297 CONFIG_SPL_STACK_R_ADDR points into SDRAM
298 - preloader_console_init() can be called here - typically this is
299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
300 spl_board_init() function containing this call
301 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_A003399_NOR_WORKAROUND
378 Enables a workaround for IFC erratum A003399. It is only
379 required during NOR boot.
381 CONFIG_A008044_WORKAROUND
382 Enables a workaround for T1040/T1042 erratum A008044. It is only
383 required during NAND boot and valid for Rev 1.0 SoC revision
385 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
387 This is the value to write into CCSR offset 0x18600
388 according to the A004510 workaround.
390 CONFIG_SYS_FSL_DSP_DDR_ADDR
391 This value denotes start offset of DDR memory which is
392 connected exclusively to the DSP cores.
394 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
395 This value denotes start offset of M2 memory
396 which is directly connected to the DSP core.
398 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
399 This value denotes start offset of M3 memory which is directly
400 connected to the DSP core.
402 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
403 This value denotes start offset of DSP CCSR space.
405 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
406 Single Source Clock is clocking mode present in some of FSL SoC's.
407 In this mode, a single differential clock is used to supply
408 clocks to the sysclock, ddrclock and usbclock.
410 CONFIG_SYS_CPC_REINIT_F
411 This CONFIG is defined when the CPC is configured as SRAM at the
412 time of U-Boot entry and is required to be re-initialized.
415 Indicates this SoC supports deep sleep feature. If deep sleep is
416 supported, core will start to execute uboot when wakes up.
418 - Generic CPU options:
419 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
421 Defines the endianess of the CPU. Implementation of those
422 values is arch specific.
425 Freescale DDR driver in use. This type of DDR controller is
426 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
428 CONFIG_SYS_FSL_DDR_ADDR
429 Freescale DDR memory-mapped register base.
431 CONFIG_SYS_FSL_DDR_EMU
432 Specify emulator support for DDR. Some DDR features such as
433 deskew training are not available.
435 CONFIG_SYS_FSL_DDRC_GEN1
436 Freescale DDR1 controller.
438 CONFIG_SYS_FSL_DDRC_GEN2
439 Freescale DDR2 controller.
441 CONFIG_SYS_FSL_DDRC_GEN3
442 Freescale DDR3 controller.
444 CONFIG_SYS_FSL_DDRC_GEN4
445 Freescale DDR4 controller.
447 CONFIG_SYS_FSL_DDRC_ARM_GEN3
448 Freescale DDR3 controller for ARM-based SoCs.
451 Board config to use DDR1. It can be enabled for SoCs with
452 Freescale DDR1 or DDR2 controllers, depending on the board
456 Board config to use DDR2. It can be enabled for SoCs with
457 Freescale DDR2 or DDR3 controllers, depending on the board
461 Board config to use DDR3. It can be enabled for SoCs with
462 Freescale DDR3 or DDR3L controllers.
465 Board config to use DDR3L. 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_DDR_BE
481 Defines the DDR controller register space as Big Endian
483 CONFIG_SYS_FSL_DDR_LE
484 Defines the DDR controller register space as Little Endian
486 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
487 Physical address from the view of DDR controllers. It is the
488 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
489 it could be different for ARM SoCs.
491 CONFIG_SYS_FSL_DDR_INTLV_256B
492 DDR controller interleaving on 256-byte. This is a special
493 interleaving mode, handled by Dickens for Freescale layerscape
496 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
497 Number of controllers used as main memory.
499 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
500 Number of controllers used for other than main memory.
502 CONFIG_SYS_FSL_HAS_DP_DDR
503 Defines the SoC has DP-DDR used for DPAA.
505 CONFIG_SYS_FSL_SEC_BE
506 Defines the SEC controller register space as Big Endian
508 CONFIG_SYS_FSL_SEC_LE
509 Defines the SEC controller register space as Little Endian
512 CONFIG_SYS_INIT_SP_OFFSET
514 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
515 pointer. This is needed for the temporary stack before
518 CONFIG_XWAY_SWAP_BYTES
520 Enable compilation of tools/xway-swap-bytes needed for Lantiq
521 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
522 be swapped if a flash programmer is used.
525 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
527 Select high exception vectors of the ARM core, e.g., do not
528 clear the V bit of the c1 register of CP15.
531 Generic timer clock source frequency.
533 COUNTER_FREQUENCY_REAL
534 Generic timer clock source frequency if the real clock is
535 different from COUNTER_FREQUENCY, and can only be determined
539 CONFIG_TEGRA_SUPPORT_NON_SECURE
541 Support executing U-Boot in non-secure (NS) mode. Certain
542 impossible actions will be skipped if the CPU is in NS mode,
543 such as ARM architectural timer initialization.
545 - Linux Kernel Interface:
546 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
548 When transferring memsize parameter to Linux, some versions
549 expect it to be in bytes, others in MB.
550 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
554 New kernel versions are expecting firmware settings to be
555 passed using flattened device trees (based on open firmware
559 * New libfdt-based support
560 * Adds the "fdt" command
561 * The bootm command automatically updates the fdt
563 OF_TBCLK - The timebase frequency.
565 boards with QUICC Engines require OF_QE to set UCC MAC
568 CONFIG_OF_BOARD_SETUP
570 Board code has addition modification that it wants to make
571 to the flat device tree before handing it off to the kernel
573 CONFIG_OF_SYSTEM_SETUP
575 Other code has addition modification that it wants to make
576 to the flat device tree before handing it off to the kernel.
577 This causes ft_system_setup() to be called before booting
582 U-Boot can detect if an IDE device is present or not.
583 If not, and this new config option is activated, U-Boot
584 removes the ATA node from the DTS before booting Linux,
585 so the Linux IDE driver does not probe the device and
586 crash. This is needed for buggy hardware (uc101) where
587 no pull down resistor is connected to the signal IDE5V_DD7.
589 - vxWorks boot parameters:
591 bootvx constructs a valid bootline using the following
592 environments variables: bootdev, bootfile, ipaddr, netmask,
593 serverip, gatewayip, hostname, othbootargs.
594 It loads the vxWorks image pointed bootfile.
596 Note: If a "bootargs" environment is defined, it will override
597 the defaults discussed just above.
599 - Cache Configuration:
600 CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
602 - Cache Configuration for ARM:
603 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
605 CONFIG_SYS_PL310_BASE - Physical base address of PL310
606 controller register space
611 If you have Amba PrimeCell PL011 UARTs, set this variable to
612 the clock speed of the UARTs.
616 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
617 define this to a list of base addresses for each (supported)
618 port. See e.g. include/configs/versatile.h
620 CONFIG_SERIAL_HW_FLOW_CONTROL
622 Define this variable to enable hw flow control in serial driver.
623 Current user of this option is drivers/serial/nsl16550.c driver
625 - Serial Download Echo Mode:
627 If defined to 1, all characters received during a
628 serial download (using the "loads" command) are
629 echoed back. This might be needed by some terminal
630 emulations (like "cu"), but may as well just take
631 time on others. This setting #define's the initial
632 value of the "loads_echo" environment variable.
634 - Removal of commands
635 If no commands are needed to boot, you can disable
636 CONFIG_CMDLINE to remove them. In this case, the command line
637 will not be available, and when U-Boot wants to execute the
638 boot command (on start-up) it will call board_run_command()
639 instead. This can reduce image size significantly for very
640 simple boot procedures.
642 - Regular expression support:
644 If this variable is defined, U-Boot is linked against
645 the SLRE (Super Light Regular Expression) library,
646 which adds regex support to some commands, as for
647 example "env grep" and "setexpr".
651 If this variable is defined, it enables watchdog
652 support for the SoC. There must be support in the SoC
653 specific code for a watchdog. For the 8xx
654 CPUs, the SIU Watchdog feature is enabled in the SYPCR
655 register. When supported for a specific SoC is
656 available, then no further board specific code should
660 When using a watchdog circuitry external to the used
661 SoC, then define this variable and provide board
662 specific code for the "hw_watchdog_reset" function.
664 CONFIG_SYS_WATCHDOG_FREQ
665 Some platforms automatically call WATCHDOG_RESET()
666 from the timer interrupt handler every
667 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
668 board configuration file, a default of CONFIG_SYS_HZ/2
669 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
670 to 0 disables calling WATCHDOG_RESET() from the timer
675 When CONFIG_CMD_DATE is selected, the type of the RTC
676 has to be selected, too. Define exactly one of the
679 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
680 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
681 CONFIG_RTC_MC146818 - use MC146818 RTC
682 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
683 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
684 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
685 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
686 CONFIG_RTC_DS164x - use Dallas DS164x RTC
687 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
688 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
689 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
690 CONFIG_SYS_RV3029_TCR - enable trickle charger on
693 Note that if the RTC uses I2C, then the I2C interface
694 must also be configured. See I2C Support, below.
697 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
699 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
700 chip-ngpio pairs that tell the PCA953X driver the number of
701 pins supported by a particular chip.
703 Note that if the GPIO device uses I2C, then the I2C interface
704 must also be configured. See I2C Support, below.
707 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
708 accesses and can checksum them or write a list of them out
709 to memory. See the 'iotrace' command for details. This is
710 useful for testing device drivers since it can confirm that
711 the driver behaves the same way before and after a code
712 change. Currently this is supported on sandbox and arm. To
713 add support for your architecture, add '#include <iotrace.h>'
714 to the bottom of arch/<arch>/include/asm/io.h and test.
716 Example output from the 'iotrace stats' command is below.
717 Note that if the trace buffer is exhausted, the checksum will
718 still continue to operate.
721 Start: 10000000 (buffer start address)
722 Size: 00010000 (buffer size)
723 Offset: 00000120 (current buffer offset)
724 Output: 10000120 (start + offset)
725 Count: 00000018 (number of trace records)
726 CRC32: 9526fb66 (CRC32 of all trace records)
730 When CONFIG_TIMESTAMP is selected, the timestamp
731 (date and time) of an image is printed by image
732 commands like bootm or iminfo. This option is
733 automatically enabled when you select CONFIG_CMD_DATE .
735 - Partition Labels (disklabels) Supported:
736 Zero or more of the following:
737 CONFIG_MAC_PARTITION Apple's MacOS partition table.
738 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
739 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
740 bootloader. Note 2TB partition limit; see
742 CONFIG_SCSI) you must configure support for at
743 least one non-MTD partition type as well.
746 CONFIG_IDE_RESET - is this is defined, IDE Reset will
747 be performed by calling the function
748 ide_set_reset(int reset)
749 which has to be defined in a board specific file
754 Set this to enable ATAPI support.
759 Set this to enable support for disks larger than 137GB
760 Also look at CONFIG_SYS_64BIT_LBA.
761 Whithout these , LBA48 support uses 32bit variables and will 'only'
762 support disks up to 2.1TB.
764 CONFIG_SYS_64BIT_LBA:
765 When enabled, makes the IDE subsystem use 64bit sector addresses.
769 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
770 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
771 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
772 maximum numbers of LUNs, SCSI ID's and target
775 The environment variable 'scsidevs' is set to the number of
776 SCSI devices found during the last scan.
778 - NETWORK Support (PCI):
780 Utility code for direct access to the SPI bus on Intel 8257x.
781 This does not do anything useful unless you set at least one
782 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
785 Support for National dp83815 chips.
788 Support for National dp8382[01] gigabit chips.
790 - NETWORK Support (other):
792 Support for the Calxeda XGMAC device
795 Support for SMSC's LAN91C96 chips.
797 CONFIG_LAN91C96_USE_32_BIT
798 Define this to enable 32 bit addressing
801 Support for SMSC's LAN91C111 chip
804 Define this to hold the physical address
805 of the device (I/O space)
807 CONFIG_SMC_USE_32_BIT
808 Define this if data bus is 32 bits
810 CONFIG_SMC_USE_IOFUNCS
811 Define this to use i/o functions instead of macros
812 (some hardware wont work with macros)
814 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
815 Define this if you have more then 3 PHYs.
818 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
820 CONFIG_FTGMAC100_EGIGA
821 Define this to use GE link update with gigabit PHY.
822 Define this if FTGMAC100 is connected to gigabit PHY.
823 If your system has 10/100 PHY only, it might not occur
824 wrong behavior. Because PHY usually return timeout or
825 useless data when polling gigabit status and gigabit
826 control registers. This behavior won't affect the
827 correctnessof 10/100 link speed update.
830 Support for Renesas on-chip Ethernet controller
832 CONFIG_SH_ETHER_USE_PORT
833 Define the number of ports to be used
835 CONFIG_SH_ETHER_PHY_ADDR
836 Define the ETH PHY's address
838 CONFIG_SH_ETHER_CACHE_WRITEBACK
839 If this option is set, the driver enables cache flush.
845 CONFIG_TPM_TIS_INFINEON
846 Support for Infineon i2c bus TPM devices. Only one device
847 per system is supported at this time.
849 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
850 Define the burst count bytes upper limit
853 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
855 CONFIG_TPM_ST33ZP24_I2C
856 Support for STMicroelectronics ST33ZP24 I2C devices.
857 Requires TPM_ST33ZP24 and I2C.
859 CONFIG_TPM_ST33ZP24_SPI
860 Support for STMicroelectronics ST33ZP24 SPI devices.
861 Requires TPM_ST33ZP24 and SPI.
864 Support for Atmel TWI TPM device. Requires I2C support.
867 Support for generic parallel port TPM devices. Only one device
868 per system is supported at this time.
870 CONFIG_TPM_TIS_BASE_ADDRESS
871 Base address where the generic TPM device is mapped
872 to. Contemporary x86 systems usually map it at
876 Define this to enable the TPM support library which provides
877 functional interfaces to some TPM commands.
878 Requires support for a TPM device.
880 CONFIG_TPM_AUTH_SESSIONS
881 Define this to enable authorized functions in the TPM library.
882 Requires CONFIG_TPM and CONFIG_SHA1.
885 At the moment only the UHCI host controller is
886 supported (PIP405, MIP405); define
887 CONFIG_USB_UHCI to enable it.
888 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
889 and define CONFIG_USB_STORAGE to enable the USB
892 Supported are USB Keyboards and USB Floppy drives
895 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
896 txfilltuning field in the EHCI controller on reset.
898 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
902 Define the below if you wish to use the USB console.
903 Once firmware is rebuilt from a serial console issue the
904 command "setenv stdin usbtty; setenv stdout usbtty" and
905 attach your USB cable. The Unix command "dmesg" should print
906 it has found a new device. The environment variable usbtty
907 can be set to gserial or cdc_acm to enable your device to
908 appear to a USB host as a Linux gserial device or a
909 Common Device Class Abstract Control Model serial device.
910 If you select usbtty = gserial you should be able to enumerate
912 # modprobe usbserial vendor=0xVendorID product=0xProductID
913 else if using cdc_acm, simply setting the environment
914 variable usbtty to be cdc_acm should suffice. The following
915 might be defined in YourBoardName.h
918 Define this to build a UDC device
921 Define this to have a tty type of device available to
922 talk to the UDC device
925 Define this to enable the high speed support for usb
926 device and usbtty. If this feature is enabled, a routine
927 int is_usbd_high_speed(void)
928 also needs to be defined by the driver to dynamically poll
929 whether the enumeration has succeded at high speed or full
932 If you have a USB-IF assigned VendorID then you may wish to
933 define your own vendor specific values either in BoardName.h
934 or directly in usbd_vendor_info.h. If you don't define
935 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
936 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
937 should pretend to be a Linux device to it's target host.
939 CONFIG_USBD_MANUFACTURER
940 Define this string as the name of your company for
941 - CONFIG_USBD_MANUFACTURER "my company"
943 CONFIG_USBD_PRODUCT_NAME
944 Define this string as the name of your product
945 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
948 Define this as your assigned Vendor ID from the USB
949 Implementors Forum. This *must* be a genuine Vendor ID
950 to avoid polluting the USB namespace.
951 - CONFIG_USBD_VENDORID 0xFFFF
953 CONFIG_USBD_PRODUCTID
954 Define this as the unique Product ID
956 - CONFIG_USBD_PRODUCTID 0xFFFF
958 - ULPI Layer Support:
959 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
960 the generic ULPI layer. The generic layer accesses the ULPI PHY
961 via the platform viewport, so you need both the genric layer and
962 the viewport enabled. Currently only Chipidea/ARC based
963 viewport is supported.
964 To enable the ULPI layer support, define CONFIG_USB_ULPI and
965 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
966 If your ULPI phy needs a different reference clock than the
967 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
968 the appropriate value in Hz.
971 The MMC controller on the Intel PXA is supported. To
972 enable this define CONFIG_MMC. The MMC can be
973 accessed from the boot prompt by mapping the device
974 to physical memory similar to flash. Command line is
975 enabled with CONFIG_CMD_MMC. The MMC driver also works with
976 the FAT fs. This is enabled with CONFIG_CMD_FAT.
979 Support for Renesas on-chip MMCIF controller
982 Define the base address of MMCIF registers
985 Define the clock frequency for MMCIF
987 - USB Device Firmware Update (DFU) class support:
989 This enables the USB portion of the DFU USB class
992 This enables support for exposing NAND devices via DFU.
995 This enables support for exposing RAM via DFU.
996 Note: DFU spec refer to non-volatile memory usage, but
997 allow usages beyond the scope of spec - here RAM usage,
998 one that would help mostly the developer.
1000 CONFIG_SYS_DFU_DATA_BUF_SIZE
1001 Dfu transfer uses a buffer before writing data to the
1002 raw storage device. Make the size (in bytes) of this buffer
1003 configurable. The size of this buffer is also configurable
1004 through the "dfu_bufsiz" environment variable.
1006 CONFIG_SYS_DFU_MAX_FILE_SIZE
1007 When updating files rather than the raw storage device,
1008 we use a static buffer to copy the file into and then write
1009 the buffer once we've been given the whole file. Define
1010 this to the maximum filesize (in bytes) for the buffer.
1011 Default is 4 MiB if undefined.
1013 DFU_DEFAULT_POLL_TIMEOUT
1014 Poll timeout [ms], is the timeout a device can send to the
1015 host. The host must wait for this timeout before sending
1016 a subsequent DFU_GET_STATUS request to the device.
1018 DFU_MANIFEST_POLL_TIMEOUT
1019 Poll timeout [ms], which the device sends to the host when
1020 entering dfuMANIFEST state. Host waits this timeout, before
1021 sending again an USB request to the device.
1023 - Journaling Flash filesystem support:
1025 Define these for a default partition on a NAND device
1027 CONFIG_SYS_JFFS2_FIRST_SECTOR,
1028 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1029 Define these for a default partition on a NOR device
1032 See Kconfig help for available keyboard drivers.
1036 Enable the Freescale DIU video driver. Reference boards for
1037 SOCs that have a DIU should define this macro to enable DIU
1038 support, and should also define these other macros:
1043 CONFIG_VIDEO_SW_CURSOR
1044 CONFIG_VGA_AS_SINGLE_DEVICE
1046 CONFIG_VIDEO_BMP_LOGO
1048 The DIU driver will look for the 'video-mode' environment
1049 variable, and if defined, enable the DIU as a console during
1050 boot. See the documentation file doc/README.video for a
1051 description of this variable.
1053 - LCD Support: CONFIG_LCD
1055 Define this to enable LCD support (for output to LCD
1056 display); also select one of the supported displays
1057 by defining one of these:
1061 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1063 CONFIG_NEC_NL6448AC33:
1065 NEC NL6448AC33-18. Active, color, single scan.
1067 CONFIG_NEC_NL6448BC20
1069 NEC NL6448BC20-08. 6.5", 640x480.
1070 Active, color, single scan.
1072 CONFIG_NEC_NL6448BC33_54
1074 NEC NL6448BC33-54. 10.4", 640x480.
1075 Active, color, single scan.
1079 Sharp 320x240. Active, color, single scan.
1080 It isn't 16x9, and I am not sure what it is.
1082 CONFIG_SHARP_LQ64D341
1084 Sharp LQ64D341 display, 640x480.
1085 Active, color, single scan.
1089 HLD1045 display, 640x480.
1090 Active, color, single scan.
1094 Optrex CBL50840-2 NF-FW 99 22 M5
1096 Hitachi LMG6912RPFC-00T
1100 320x240. Black & white.
1102 CONFIG_LCD_ALIGNMENT
1104 Normally the LCD is page-aligned (typically 4KB). If this is
1105 defined then the LCD will be aligned to this value instead.
1106 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1107 here, since it is cheaper to change data cache settings on
1108 a per-section basis.
1113 Sometimes, for example if the display is mounted in portrait
1114 mode or even if it's mounted landscape but rotated by 180degree,
1115 we need to rotate our content of the display relative to the
1116 framebuffer, so that user can read the messages which are
1118 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1119 initialized with a given rotation from "vl_rot" out of
1120 "vidinfo_t" which is provided by the board specific code.
1121 The value for vl_rot is coded as following (matching to
1122 fbcon=rotate:<n> linux-kernel commandline):
1123 0 = no rotation respectively 0 degree
1124 1 = 90 degree rotation
1125 2 = 180 degree rotation
1126 3 = 270 degree rotation
1128 If CONFIG_LCD_ROTATION is not defined, the console will be
1129 initialized with 0degree rotation.
1133 Support drawing of RLE8-compressed bitmaps on the LCD.
1136 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1138 The clock frequency of the MII bus
1140 CONFIG_PHY_RESET_DELAY
1142 Some PHY like Intel LXT971A need extra delay after
1143 reset before any MII register access is possible.
1144 For such PHY, set this option to the usec delay
1145 required. (minimum 300usec for LXT971A)
1147 CONFIG_PHY_CMD_DELAY (ppc4xx)
1149 Some PHY like Intel LXT971A need extra delay after
1150 command issued before MII status register can be read
1155 Define a default value for the IP address to use for
1156 the default Ethernet interface, in case this is not
1157 determined through e.g. bootp.
1158 (Environment variable "ipaddr")
1160 - Server IP address:
1163 Defines a default value for the IP address of a TFTP
1164 server to contact when using the "tftboot" command.
1165 (Environment variable "serverip")
1167 CONFIG_KEEP_SERVERADDR
1169 Keeps the server's MAC address, in the env 'serveraddr'
1170 for passing to bootargs (like Linux's netconsole option)
1172 - Gateway IP address:
1175 Defines a default value for the IP address of the
1176 default router where packets to other networks are
1178 (Environment variable "gatewayip")
1183 Defines a default value for the subnet mask (or
1184 routing prefix) which is used to determine if an IP
1185 address belongs to the local subnet or needs to be
1186 forwarded through a router.
1187 (Environment variable "netmask")
1189 - BOOTP Recovery Mode:
1190 CONFIG_BOOTP_RANDOM_DELAY
1192 If you have many targets in a network that try to
1193 boot using BOOTP, you may want to avoid that all
1194 systems send out BOOTP requests at precisely the same
1195 moment (which would happen for instance at recovery
1196 from a power failure, when all systems will try to
1197 boot, thus flooding the BOOTP server. Defining
1198 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1199 inserted before sending out BOOTP requests. The
1200 following delays are inserted then:
1202 1st BOOTP request: delay 0 ... 1 sec
1203 2nd BOOTP request: delay 0 ... 2 sec
1204 3rd BOOTP request: delay 0 ... 4 sec
1206 BOOTP requests: delay 0 ... 8 sec
1208 CONFIG_BOOTP_ID_CACHE_SIZE
1210 BOOTP packets are uniquely identified using a 32-bit ID. The
1211 server will copy the ID from client requests to responses and
1212 U-Boot will use this to determine if it is the destination of
1213 an incoming response. Some servers will check that addresses
1214 aren't in use before handing them out (usually using an ARP
1215 ping) and therefore take up to a few hundred milliseconds to
1216 respond. Network congestion may also influence the time it
1217 takes for a response to make it back to the client. If that
1218 time is too long, U-Boot will retransmit requests. In order
1219 to allow earlier responses to still be accepted after these
1220 retransmissions, U-Boot's BOOTP client keeps a small cache of
1221 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1222 cache. The default is to keep IDs for up to four outstanding
1223 requests. Increasing this will allow U-Boot to accept offers
1224 from a BOOTP client in networks with unusually high latency.
1226 - DHCP Advanced Options:
1227 You can fine tune the DHCP functionality by defining
1228 CONFIG_BOOTP_* symbols:
1230 CONFIG_BOOTP_NISDOMAIN
1231 CONFIG_BOOTP_BOOTFILESIZE
1232 CONFIG_BOOTP_NTPSERVER
1233 CONFIG_BOOTP_TIMEOFFSET
1234 CONFIG_BOOTP_VENDOREX
1235 CONFIG_BOOTP_MAY_FAIL
1237 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1238 environment variable, not the BOOTP server.
1240 CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1241 after the configured retry count, the call will fail
1242 instead of starting over. This can be used to fail over
1243 to Link-local IP address configuration if the DHCP server
1246 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1248 A 32bit value in microseconds for a delay between
1249 receiving a "DHCP Offer" and sending the "DHCP Request".
1250 This fixes a problem with certain DHCP servers that don't
1251 respond 100% of the time to a "DHCP request". E.g. On an
1252 AT91RM9200 processor running at 180MHz, this delay needed
1253 to be *at least* 15,000 usec before a Windows Server 2003
1254 DHCP server would reply 100% of the time. I recommend at
1255 least 50,000 usec to be safe. The alternative is to hope
1256 that one of the retries will be successful but note that
1257 the DHCP timeout and retry process takes a longer than
1260 - Link-local IP address negotiation:
1261 Negotiate with other link-local clients on the local network
1262 for an address that doesn't require explicit configuration.
1263 This is especially useful if a DHCP server cannot be guaranteed
1264 to exist in all environments that the device must operate.
1266 See doc/README.link-local for more information.
1268 - MAC address from environment variables
1270 FDT_SEQ_MACADDR_FROM_ENV
1272 Fix-up device tree with MAC addresses fetched sequentially from
1273 environment variables. This config work on assumption that
1274 non-usable ethernet node of device-tree are either not present
1275 or their status has been marked as "disabled".
1278 CONFIG_CDP_DEVICE_ID
1280 The device id used in CDP trigger frames.
1282 CONFIG_CDP_DEVICE_ID_PREFIX
1284 A two character string which is prefixed to the MAC address
1289 A printf format string which contains the ascii name of
1290 the port. Normally is set to "eth%d" which sets
1291 eth0 for the first Ethernet, eth1 for the second etc.
1293 CONFIG_CDP_CAPABILITIES
1295 A 32bit integer which indicates the device capabilities;
1296 0x00000010 for a normal host which does not forwards.
1300 An ascii string containing the version of the software.
1304 An ascii string containing the name of the platform.
1308 A 32bit integer sent on the trigger.
1310 CONFIG_CDP_POWER_CONSUMPTION
1312 A 16bit integer containing the power consumption of the
1313 device in .1 of milliwatts.
1315 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1317 A byte containing the id of the VLAN.
1319 - Status LED: CONFIG_LED_STATUS
1321 Several configurations allow to display the current
1322 status using a LED. For instance, the LED will blink
1323 fast while running U-Boot code, stop blinking as
1324 soon as a reply to a BOOTP request was received, and
1325 start blinking slow once the Linux kernel is running
1326 (supported by a status LED driver in the Linux
1327 kernel). Defining CONFIG_LED_STATUS enables this
1332 CONFIG_LED_STATUS_GPIO
1333 The status LED can be connected to a GPIO pin.
1334 In such cases, the gpio_led driver can be used as a
1335 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1336 to include the gpio_led driver in the U-Boot binary.
1338 CONFIG_GPIO_LED_INVERTED_TABLE
1339 Some GPIO connected LEDs may have inverted polarity in which
1340 case the GPIO high value corresponds to LED off state and
1341 GPIO low value corresponds to LED on state.
1342 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1343 with a list of GPIO LEDs that have inverted polarity.
1346 CONFIG_SYS_NUM_I2C_BUSES
1347 Hold the number of i2c buses you want to use.
1349 CONFIG_SYS_I2C_DIRECT_BUS
1350 define this, if you don't use i2c muxes on your hardware.
1351 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1354 CONFIG_SYS_I2C_MAX_HOPS
1355 define how many muxes are maximal consecutively connected
1356 on one i2c bus. If you not use i2c muxes, omit this
1359 CONFIG_SYS_I2C_BUSES
1360 hold a list of buses you want to use, only used if
1361 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1362 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1363 CONFIG_SYS_NUM_I2C_BUSES = 9:
1365 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1366 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1367 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1368 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1369 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1370 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1371 {1, {I2C_NULL_HOP}}, \
1372 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1373 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1377 bus 0 on adapter 0 without a mux
1378 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1379 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1380 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1381 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1382 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1383 bus 6 on adapter 1 without a mux
1384 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1385 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1387 If you do not have i2c muxes on your board, omit this define.
1389 - Legacy I2C Support:
1390 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1391 then the following macros need to be defined (examples are
1392 from include/configs/lwmon.h):
1396 (Optional). Any commands necessary to enable the I2C
1397 controller or configure ports.
1399 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1403 The code necessary to make the I2C data line active
1404 (driven). If the data line is open collector, this
1407 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1411 The code necessary to make the I2C data line tri-stated
1412 (inactive). If the data line is open collector, this
1415 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1419 Code that returns true if the I2C data line is high,
1422 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1426 If <bit> is true, sets the I2C data line high. If it
1427 is false, it clears it (low).
1429 eg: #define I2C_SDA(bit) \
1430 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1431 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1435 If <bit> is true, sets the I2C clock line high. If it
1436 is false, it clears it (low).
1438 eg: #define I2C_SCL(bit) \
1439 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1440 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1444 This delay is invoked four times per clock cycle so this
1445 controls the rate of data transfer. The data rate thus
1446 is 1 / (I2C_DELAY * 4). Often defined to be something
1449 #define I2C_DELAY udelay(2)
1451 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1453 If your arch supports the generic GPIO framework (asm/gpio.h),
1454 then you may alternatively define the two GPIOs that are to be
1455 used as SCL / SDA. Any of the previous I2C_xxx macros will
1456 have GPIO-based defaults assigned to them as appropriate.
1458 You should define these to the GPIO value as given directly to
1459 the generic GPIO functions.
1461 CONFIG_SYS_I2C_INIT_BOARD
1463 When a board is reset during an i2c bus transfer
1464 chips might think that the current transfer is still
1465 in progress. On some boards it is possible to access
1466 the i2c SCLK line directly, either by using the
1467 processor pin as a GPIO or by having a second pin
1468 connected to the bus. If this option is defined a
1469 custom i2c_init_board() routine in boards/xxx/board.c
1470 is run early in the boot sequence.
1472 CONFIG_I2C_MULTI_BUS
1474 This option allows the use of multiple I2C buses, each of which
1475 must have a controller. At any point in time, only one bus is
1476 active. To switch to a different bus, use the 'i2c dev' command.
1477 Note that bus numbering is zero-based.
1479 CONFIG_SYS_I2C_NOPROBES
1481 This option specifies a list of I2C devices that will be skipped
1482 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1483 is set, specify a list of bus-device pairs. Otherwise, specify
1484 a 1D array of device addresses
1487 #undef CONFIG_I2C_MULTI_BUS
1488 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1490 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1492 #define CONFIG_I2C_MULTI_BUS
1493 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1495 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1497 CONFIG_SYS_SPD_BUS_NUM
1499 If defined, then this indicates the I2C bus number for DDR SPD.
1500 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1502 CONFIG_SYS_RTC_BUS_NUM
1504 If defined, then this indicates the I2C bus number for the RTC.
1505 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1507 CONFIG_SOFT_I2C_READ_REPEATED_START
1509 defining this will force the i2c_read() function in
1510 the soft_i2c driver to perform an I2C repeated start
1511 between writing the address pointer and reading the
1512 data. If this define is omitted the default behaviour
1513 of doing a stop-start sequence will be used. Most I2C
1514 devices can use either method, but some require one or
1517 - SPI Support: CONFIG_SPI
1519 Enables SPI driver (so far only tested with
1520 SPI EEPROM, also an instance works with Crystal A/D and
1521 D/As on the SACSng board)
1525 Enables a software (bit-bang) SPI driver rather than
1526 using hardware support. This is a general purpose
1527 driver that only requires three general I/O port pins
1528 (two outputs, one input) to function. If this is
1529 defined, the board configuration must define several
1530 SPI configuration items (port pins to use, etc). For
1531 an example, see include/configs/sacsng.h.
1533 CONFIG_SYS_SPI_MXC_WAIT
1534 Timeout for waiting until spi transfer completed.
1535 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1537 - FPGA Support: CONFIG_FPGA
1539 Enables FPGA subsystem.
1541 CONFIG_FPGA_<vendor>
1543 Enables support for specific chip vendors.
1546 CONFIG_FPGA_<family>
1548 Enables support for FPGA family.
1549 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1553 Specify the number of FPGA devices to support.
1555 CONFIG_SYS_FPGA_PROG_FEEDBACK
1557 Enable printing of hash marks during FPGA configuration.
1559 CONFIG_SYS_FPGA_CHECK_BUSY
1561 Enable checks on FPGA configuration interface busy
1562 status by the configuration function. This option
1563 will require a board or device specific function to
1568 If defined, a function that provides delays in the FPGA
1569 configuration driver.
1571 CONFIG_SYS_FPGA_CHECK_CTRLC
1572 Allow Control-C to interrupt FPGA configuration
1574 CONFIG_SYS_FPGA_CHECK_ERROR
1576 Check for configuration errors during FPGA bitfile
1577 loading. For example, abort during Virtex II
1578 configuration if the INIT_B line goes low (which
1579 indicated a CRC error).
1581 CONFIG_SYS_FPGA_WAIT_INIT
1583 Maximum time to wait for the INIT_B line to de-assert
1584 after PROB_B has been de-asserted during a Virtex II
1585 FPGA configuration sequence. The default time is 500
1588 CONFIG_SYS_FPGA_WAIT_BUSY
1590 Maximum time to wait for BUSY to de-assert during
1591 Virtex II FPGA configuration. The default is 5 ms.
1593 CONFIG_SYS_FPGA_WAIT_CONFIG
1595 Time to wait after FPGA configuration. The default is
1598 - Configuration Management:
1602 If defined, this string will be added to the U-Boot
1603 version information (U_BOOT_VERSION)
1605 - Vendor Parameter Protection:
1607 U-Boot considers the values of the environment
1608 variables "serial#" (Board Serial Number) and
1609 "ethaddr" (Ethernet Address) to be parameters that
1610 are set once by the board vendor / manufacturer, and
1611 protects these variables from casual modification by
1612 the user. Once set, these variables are read-only,
1613 and write or delete attempts are rejected. You can
1614 change this behaviour:
1616 If CONFIG_ENV_OVERWRITE is #defined in your config
1617 file, the write protection for vendor parameters is
1618 completely disabled. Anybody can change or delete
1621 Alternatively, if you define _both_ an ethaddr in the
1622 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1623 Ethernet address is installed in the environment,
1624 which can be changed exactly ONCE by the user. [The
1625 serial# is unaffected by this, i. e. it remains
1628 The same can be accomplished in a more flexible way
1629 for any variable by configuring the type of access
1630 to allow for those variables in the ".flags" variable
1631 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1636 Define this variable to enable the reservation of
1637 "protected RAM", i. e. RAM which is not overwritten
1638 by U-Boot. Define CONFIG_PRAM to hold the number of
1639 kB you want to reserve for pRAM. You can overwrite
1640 this default value by defining an environment
1641 variable "pram" to the number of kB you want to
1642 reserve. Note that the board info structure will
1643 still show the full amount of RAM. If pRAM is
1644 reserved, a new environment variable "mem" will
1645 automatically be defined to hold the amount of
1646 remaining RAM in a form that can be passed as boot
1647 argument to Linux, for instance like that:
1649 setenv bootargs ... mem=\${mem}
1652 This way you can tell Linux not to use this memory,
1653 either, which results in a memory region that will
1654 not be affected by reboots.
1656 *WARNING* If your board configuration uses automatic
1657 detection of the RAM size, you must make sure that
1658 this memory test is non-destructive. So far, the
1659 following board configurations are known to be
1662 IVMS8, IVML24, SPD8xx,
1663 HERMES, IP860, RPXlite, LWMON,
1667 CONFIG_NET_RETRY_COUNT
1669 This variable defines the number of retries for
1670 network operations like ARP, RARP, TFTP, or BOOTP
1671 before giving up the operation. If not defined, a
1672 default value of 5 is used.
1676 Timeout waiting for an ARP reply in milliseconds.
1680 Timeout in milliseconds used in NFS protocol.
1681 If you encounter "ERROR: Cannot umount" in nfs command,
1682 try longer timeout such as
1683 #define CONFIG_NFS_TIMEOUT 10000UL
1687 In the current implementation, the local variables
1688 space and global environment variables space are
1689 separated. Local variables are those you define by
1690 simply typing `name=value'. To access a local
1691 variable later on, you have write `$name' or
1692 `${name}'; to execute the contents of a variable
1693 directly type `$name' at the command prompt.
1695 Global environment variables are those you use
1696 setenv/printenv to work with. To run a command stored
1697 in such a variable, you need to use the run command,
1698 and you must not use the '$' sign to access them.
1700 To store commands and special characters in a
1701 variable, please use double quotation marks
1702 surrounding the whole text of the variable, instead
1703 of the backslashes before semicolons and special
1706 - Command Line Editing and History:
1707 CONFIG_CMDLINE_PS_SUPPORT
1709 Enable support for changing the command prompt string
1710 at run-time. Only static string is supported so far.
1711 The string is obtained from environment variables PS1
1714 - Default Environment:
1715 CONFIG_EXTRA_ENV_SETTINGS
1717 Define this to contain any number of null terminated
1718 strings (variable = value pairs) that will be part of
1719 the default environment compiled into the boot image.
1721 For example, place something like this in your
1722 board's config file:
1724 #define CONFIG_EXTRA_ENV_SETTINGS \
1728 Warning: This method is based on knowledge about the
1729 internal format how the environment is stored by the
1730 U-Boot code. This is NOT an official, exported
1731 interface! Although it is unlikely that this format
1732 will change soon, there is no guarantee either.
1733 You better know what you are doing here.
1735 Note: overly (ab)use of the default environment is
1736 discouraged. Make sure to check other ways to preset
1737 the environment like the "source" command or the
1740 CONFIG_DELAY_ENVIRONMENT
1742 Normally the environment is loaded when the board is
1743 initialised so that it is available to U-Boot. This inhibits
1744 that so that the environment is not available until
1745 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1746 this is instead controlled by the value of
1747 /config/load-environment.
1749 - TFTP Fixed UDP Port:
1752 If this is defined, the environment variable tftpsrcp
1753 is used to supply the TFTP UDP source port value.
1754 If tftpsrcp isn't defined, the normal pseudo-random port
1755 number generator is used.
1757 Also, the environment variable tftpdstp is used to supply
1758 the TFTP UDP destination port value. If tftpdstp isn't
1759 defined, the normal port 69 is used.
1761 The purpose for tftpsrcp is to allow a TFTP server to
1762 blindly start the TFTP transfer using the pre-configured
1763 target IP address and UDP port. This has the effect of
1764 "punching through" the (Windows XP) firewall, allowing
1765 the remainder of the TFTP transfer to proceed normally.
1766 A better solution is to properly configure the firewall,
1767 but sometimes that is not allowed.
1769 CONFIG_STANDALONE_LOAD_ADDR
1771 This option defines a board specific value for the
1772 address where standalone program gets loaded, thus
1773 overwriting the architecture dependent default
1776 - Frame Buffer Address:
1779 Define CONFIG_FB_ADDR if you want to use specific
1780 address for frame buffer. This is typically the case
1781 when using a graphics controller has separate video
1782 memory. U-Boot will then place the frame buffer at
1783 the given address instead of dynamically reserving it
1784 in system RAM by calling lcd_setmem(), which grabs
1785 the memory for the frame buffer depending on the
1786 configured panel size.
1788 Please see board_init_f function.
1790 - Automatic software updates via TFTP server
1792 CONFIG_UPDATE_TFTP_CNT_MAX
1793 CONFIG_UPDATE_TFTP_MSEC_MAX
1795 These options enable and control the auto-update feature;
1796 for a more detailed description refer to doc/README.update.
1798 - MTD Support (mtdparts command, UBI support)
1799 CONFIG_MTD_UBI_WL_THRESHOLD
1800 This parameter defines the maximum difference between the highest
1801 erase counter value and the lowest erase counter value of eraseblocks
1802 of UBI devices. When this threshold is exceeded, UBI starts performing
1803 wear leveling by means of moving data from eraseblock with low erase
1804 counter to eraseblocks with high erase counter.
1806 The default value should be OK for SLC NAND flashes, NOR flashes and
1807 other flashes which have eraseblock life-cycle 100000 or more.
1808 However, in case of MLC NAND flashes which typically have eraseblock
1809 life-cycle less than 10000, the threshold should be lessened (e.g.,
1810 to 128 or 256, although it does not have to be power of 2).
1814 CONFIG_MTD_UBI_BEB_LIMIT
1815 This option specifies the maximum bad physical eraseblocks UBI
1816 expects on the MTD device (per 1024 eraseblocks). If the
1817 underlying flash does not admit of bad eraseblocks (e.g. NOR
1818 flash), this value is ignored.
1820 NAND datasheets often specify the minimum and maximum NVM
1821 (Number of Valid Blocks) for the flashes' endurance lifetime.
1822 The maximum expected bad eraseblocks per 1024 eraseblocks
1823 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1824 which gives 20 for most NANDs (MaxNVB is basically the total
1825 count of eraseblocks on the chip).
1827 To put it differently, if this value is 20, UBI will try to
1828 reserve about 1.9% of physical eraseblocks for bad blocks
1829 handling. And that will be 1.9% of eraseblocks on the entire
1830 NAND chip, not just the MTD partition UBI attaches. This means
1831 that if you have, say, a NAND flash chip admits maximum 40 bad
1832 eraseblocks, and it is split on two MTD partitions of the same
1833 size, UBI will reserve 40 eraseblocks when attaching a
1838 CONFIG_MTD_UBI_FASTMAP
1839 Fastmap is a mechanism which allows attaching an UBI device
1840 in nearly constant time. Instead of scanning the whole MTD device it
1841 only has to locate a checkpoint (called fastmap) on the device.
1842 The on-flash fastmap contains all information needed to attach
1843 the device. Using fastmap makes only sense on large devices where
1844 attaching by scanning takes long. UBI will not automatically install
1845 a fastmap on old images, but you can set the UBI parameter
1846 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1847 that fastmap-enabled images are still usable with UBI implementations
1848 without fastmap support. On typical flash devices the whole fastmap
1849 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1851 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1852 Set this parameter to enable fastmap automatically on images
1856 CONFIG_MTD_UBI_FM_DEBUG
1857 Enable UBI fastmap debug
1862 Enable building of SPL globally.
1864 CONFIG_SPL_MAX_FOOTPRINT
1865 Maximum size in memory allocated to the SPL, BSS included.
1866 When defined, the linker checks that the actual memory
1867 used by SPL from _start to __bss_end does not exceed it.
1868 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1869 must not be both defined at the same time.
1872 Maximum size of the SPL image (text, data, rodata, and
1873 linker lists sections), BSS excluded.
1874 When defined, the linker checks that the actual size does
1877 CONFIG_SPL_RELOC_TEXT_BASE
1878 Address to relocate to. If unspecified, this is equal to
1879 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1881 CONFIG_SPL_BSS_START_ADDR
1882 Link address for the BSS within the SPL binary.
1884 CONFIG_SPL_BSS_MAX_SIZE
1885 Maximum size in memory allocated to the SPL BSS.
1886 When defined, the linker checks that the actual memory used
1887 by SPL from __bss_start to __bss_end does not exceed it.
1888 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1889 must not be both defined at the same time.
1892 Adress of the start of the stack SPL will use
1894 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1895 When defined, SPL will panic() if the image it has
1896 loaded does not have a signature.
1897 Defining this is useful when code which loads images
1898 in SPL cannot guarantee that absolutely all read errors
1900 An example is the LPC32XX MLC NAND driver, which will
1901 consider that a completely unreadable NAND block is bad,
1902 and thus should be skipped silently.
1904 CONFIG_SPL_RELOC_STACK
1905 Adress of the start of the stack SPL will use after
1906 relocation. If unspecified, this is equal to
1909 CONFIG_SYS_SPL_MALLOC_START
1910 Starting address of the malloc pool used in SPL.
1911 When this option is set the full malloc is used in SPL and
1912 it is set up by spl_init() and before that, the simple malloc()
1913 can be used if CONFIG_SYS_MALLOC_F is defined.
1915 CONFIG_SYS_SPL_MALLOC_SIZE
1916 The size of the malloc pool used in SPL.
1918 CONFIG_SPL_DISPLAY_PRINT
1919 For ARM, enable an optional function to print more information
1920 about the running system.
1922 CONFIG_SPL_INIT_MINIMAL
1923 Arch init code should be built for a very small image
1925 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
1926 Partition on the MMC to load U-Boot from when the MMC is being
1929 CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
1930 Sector to load kernel uImage from when MMC is being
1931 used in raw mode (for Falcon mode)
1933 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1934 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1935 Sector and number of sectors to load kernel argument
1936 parameters from when MMC is being used in raw mode
1939 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1940 Filename to read to load U-Boot when reading from filesystem
1942 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1943 Filename to read to load kernel uImage when reading
1944 from filesystem (for Falcon mode)
1946 CONFIG_SPL_FS_LOAD_ARGS_NAME
1947 Filename to read to load kernel argument parameters
1948 when reading from filesystem (for Falcon mode)
1950 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1951 Set this for NAND SPL on PPC mpc83xx targets, so that
1952 start.S waits for the rest of the SPL to load before
1953 continuing (the hardware starts execution after just
1954 loading the first page rather than the full 4K).
1956 CONFIG_SPL_SKIP_RELOCATE
1957 Avoid SPL relocation
1959 CONFIG_SPL_NAND_IDENT
1960 SPL uses the chip ID list to identify the NAND flash.
1961 Requires CONFIG_SPL_NAND_BASE.
1964 Support for a lightweight UBI (fastmap) scanner and
1967 CONFIG_SPL_NAND_RAW_ONLY
1968 Support to boot only raw u-boot.bin images. Use this only
1969 if you need to save space.
1971 CONFIG_SPL_COMMON_INIT_DDR
1972 Set for common ddr init with serial presence detect in
1975 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1976 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1977 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1978 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1979 CONFIG_SYS_NAND_ECCBYTES
1980 Defines the size and behavior of the NAND that SPL uses
1983 CONFIG_SYS_NAND_U_BOOT_DST
1984 Location in memory to load U-Boot to
1986 CONFIG_SYS_NAND_U_BOOT_SIZE
1987 Size of image to load
1989 CONFIG_SYS_NAND_U_BOOT_START
1990 Entry point in loaded image to jump to
1992 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1993 Define this if you need to first read the OOB and then the
1994 data. This is used, for example, on davinci platforms.
1996 CONFIG_SPL_RAM_DEVICE
1997 Support for running image already present in ram, in SPL binary
2000 Image offset to which the SPL should be padded before appending
2001 the SPL payload. By default, this is defined as
2002 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2003 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2004 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2007 Final target image containing SPL and payload. Some SPLs
2008 use an arch-specific makefile fragment instead, for
2009 example if more than one image needs to be produced.
2011 CONFIG_SPL_FIT_PRINT
2012 Printing information about a FIT image adds quite a bit of
2013 code to SPL. So this is normally disabled in SPL. Use this
2014 option to re-enable it. This will affect the output of the
2015 bootm command when booting a FIT image.
2019 Enable building of TPL globally.
2022 Image offset to which the TPL should be padded before appending
2023 the TPL payload. By default, this is defined as
2024 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
2025 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
2026 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
2028 - Interrupt support (PPC):
2030 There are common interrupt_init() and timer_interrupt()
2031 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2032 for CPU specific initialization. interrupt_init_cpu()
2033 should set decrementer_count to appropriate value. If
2034 CPU resets decrementer automatically after interrupt
2035 (ppc4xx) it should set decrementer_count to zero.
2036 timer_interrupt() calls timer_interrupt_cpu() for CPU
2037 specific handling. If board has watchdog / status_led
2038 / other_activity_monitor it works automatically from
2039 general timer_interrupt().
2042 Board initialization settings:
2043 ------------------------------
2045 During Initialization u-boot calls a number of board specific functions
2046 to allow the preparation of board specific prerequisites, e.g. pin setup
2047 before drivers are initialized. To enable these callbacks the
2048 following configuration macros have to be defined. Currently this is
2049 architecture specific, so please check arch/your_architecture/lib/board.c
2050 typically in board_init_f() and board_init_r().
2052 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2053 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2054 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
2055 - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2057 Configuration Settings:
2058 -----------------------
2060 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
2061 Optionally it can be defined to support 64-bit memory commands.
2063 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2064 undefine this when you're short of memory.
2066 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2067 width of the commands listed in the 'help' command output.
2069 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2070 prompt for user input.
2072 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2074 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2076 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2078 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2079 the application (usually a Linux kernel) when it is
2082 - CONFIG_SYS_BAUDRATE_TABLE:
2083 List of legal baudrate settings for this board.
2085 - CONFIG_SYS_MEM_RESERVE_SECURE
2086 Only implemented for ARMv8 for now.
2087 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
2088 is substracted from total RAM and won't be reported to OS.
2089 This memory can be used as secure memory. A variable
2090 gd->arch.secure_ram is used to track the location. In systems
2091 the RAM base is not zero, or RAM is divided into banks,
2092 this variable needs to be recalcuated to get the address.
2094 - CONFIG_SYS_MEM_TOP_HIDE:
2095 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2096 this specified memory area will get subtracted from the top
2097 (end) of RAM and won't get "touched" at all by U-Boot. By
2098 fixing up gd->ram_size the Linux kernel should gets passed
2099 the now "corrected" memory size and won't touch it either.
2100 This should work for arch/ppc and arch/powerpc. Only Linux
2101 board ports in arch/powerpc with bootwrapper support that
2102 recalculate the memory size from the SDRAM controller setup
2103 will have to get fixed in Linux additionally.
2105 This option can be used as a workaround for the 440EPx/GRx
2106 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2109 WARNING: Please make sure that this value is a multiple of
2110 the Linux page size (normally 4k). If this is not the case,
2111 then the end address of the Linux memory will be located at a
2112 non page size aligned address and this could cause major
2115 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2116 Enable temporary baudrate change while serial download
2118 - CONFIG_SYS_SDRAM_BASE:
2119 Physical start address of SDRAM. _Must_ be 0 here.
2121 - CONFIG_SYS_FLASH_BASE:
2122 Physical start address of Flash memory.
2124 - CONFIG_SYS_MONITOR_BASE:
2125 Physical start address of boot monitor code (set by
2126 make config files to be same as the text base address
2127 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
2128 CONFIG_SYS_FLASH_BASE when booting from flash.
2130 - CONFIG_SYS_MONITOR_LEN:
2131 Size of memory reserved for monitor code, used to
2132 determine _at_compile_time_ (!) if the environment is
2133 embedded within the U-Boot image, or in a separate
2136 - CONFIG_SYS_MALLOC_LEN:
2137 Size of DRAM reserved for malloc() use.
2139 - CONFIG_SYS_MALLOC_F_LEN
2140 Size of the malloc() pool for use before relocation. If
2141 this is defined, then a very simple malloc() implementation
2142 will become available before relocation. The address is just
2143 below the global data, and the stack is moved down to make
2146 This feature allocates regions with increasing addresses
2147 within the region. calloc() is supported, but realloc()
2148 is not available. free() is supported but does nothing.
2149 The memory will be freed (or in fact just forgotten) when
2150 U-Boot relocates itself.
2152 - CONFIG_SYS_MALLOC_SIMPLE
2153 Provides a simple and small malloc() and calloc() for those
2154 boards which do not use the full malloc in SPL (which is
2155 enabled with CONFIG_SYS_SPL_MALLOC_START).
2157 - CONFIG_SYS_NONCACHED_MEMORY:
2158 Size of non-cached memory area. This area of memory will be
2159 typically located right below the malloc() area and mapped
2160 uncached in the MMU. This is useful for drivers that would
2161 otherwise require a lot of explicit cache maintenance. For
2162 some drivers it's also impossible to properly maintain the
2163 cache. For example if the regions that need to be flushed
2164 are not a multiple of the cache-line size, *and* padding
2165 cannot be allocated between the regions to align them (i.e.
2166 if the HW requires a contiguous array of regions, and the
2167 size of each region is not cache-aligned), then a flush of
2168 one region may result in overwriting data that hardware has
2169 written to another region in the same cache-line. This can
2170 happen for example in network drivers where descriptors for
2171 buffers are typically smaller than the CPU cache-line (e.g.
2172 16 bytes vs. 32 or 64 bytes).
2174 Non-cached memory is only supported on 32-bit ARM at present.
2176 - CONFIG_SYS_BOOTM_LEN:
2177 Normally compressed uImages are limited to an
2178 uncompressed size of 8 MBytes. If this is not enough,
2179 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2180 to adjust this setting to your needs.
2182 - CONFIG_SYS_BOOTMAPSZ:
2183 Maximum size of memory mapped by the startup code of
2184 the Linux kernel; all data that must be processed by
2185 the Linux kernel (bd_info, boot arguments, FDT blob if
2186 used) must be put below this limit, unless "bootm_low"
2187 environment variable is defined and non-zero. In such case
2188 all data for the Linux kernel must be between "bootm_low"
2189 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2190 variable "bootm_mapsize" will override the value of
2191 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2192 then the value in "bootm_size" will be used instead.
2194 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2195 Enable initrd_high functionality. If defined then the
2196 initrd_high feature is enabled and the bootm ramdisk subcommand
2199 - CONFIG_SYS_BOOT_GET_CMDLINE:
2200 Enables allocating and saving kernel cmdline in space between
2201 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2203 - CONFIG_SYS_BOOT_GET_KBD:
2204 Enables allocating and saving a kernel copy of the bd_info in
2205 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2207 - CONFIG_SYS_MAX_FLASH_BANKS:
2208 Max number of Flash memory banks
2210 - CONFIG_SYS_MAX_FLASH_SECT:
2211 Max number of sectors on a Flash chip
2213 - CONFIG_SYS_FLASH_ERASE_TOUT:
2214 Timeout for Flash erase operations (in ms)
2216 - CONFIG_SYS_FLASH_WRITE_TOUT:
2217 Timeout for Flash write operations (in ms)
2219 - CONFIG_SYS_FLASH_LOCK_TOUT
2220 Timeout for Flash set sector lock bit operation (in ms)
2222 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2223 Timeout for Flash clear lock bits operation (in ms)
2225 - CONFIG_SYS_FLASH_PROTECTION
2226 If defined, hardware flash sectors protection is used
2227 instead of U-Boot software protection.
2229 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2231 Enable TFTP transfers directly to flash memory;
2232 without this option such a download has to be
2233 performed in two steps: (1) download to RAM, and (2)
2234 copy from RAM to flash.
2236 The two-step approach is usually more reliable, since
2237 you can check if the download worked before you erase
2238 the flash, but in some situations (when system RAM is
2239 too limited to allow for a temporary copy of the
2240 downloaded image) this option may be very useful.
2242 - CONFIG_SYS_FLASH_CFI:
2243 Define if the flash driver uses extra elements in the
2244 common flash structure for storing flash geometry.
2246 - CONFIG_FLASH_CFI_DRIVER
2247 This option also enables the building of the cfi_flash driver
2248 in the drivers directory
2250 - CONFIG_FLASH_CFI_MTD
2251 This option enables the building of the cfi_mtd driver
2252 in the drivers directory. The driver exports CFI flash
2255 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2256 Use buffered writes to flash.
2258 - CONFIG_FLASH_SPANSION_S29WS_N
2259 s29ws-n MirrorBit flash has non-standard addresses for buffered
2262 - CONFIG_SYS_FLASH_QUIET_TEST
2263 If this option is defined, the common CFI flash doesn't
2264 print it's warning upon not recognized FLASH banks. This
2265 is useful, if some of the configured banks are only
2266 optionally available.
2268 - CONFIG_FLASH_SHOW_PROGRESS
2269 If defined (must be an integer), print out countdown
2270 digits and dots. Recommended value: 45 (9..1) for 80
2271 column displays, 15 (3..1) for 40 column displays.
2273 - CONFIG_FLASH_VERIFY
2274 If defined, the content of the flash (destination) is compared
2275 against the source after the write operation. An error message
2276 will be printed when the contents are not identical.
2277 Please note that this option is useless in nearly all cases,
2278 since such flash programming errors usually are detected earlier
2279 while unprotecting/erasing/programming. Please only enable
2280 this option if you really know what you are doing.
2282 - CONFIG_SYS_RX_ETH_BUFFER:
2283 Defines the number of Ethernet receive buffers. On some
2284 Ethernet controllers it is recommended to set this value
2285 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2286 buffers can be full shortly after enabling the interface
2287 on high Ethernet traffic.
2288 Defaults to 4 if not defined.
2290 - CONFIG_ENV_MAX_ENTRIES
2292 Maximum number of entries in the hash table that is used
2293 internally to store the environment settings. The default
2294 setting is supposed to be generous and should work in most
2295 cases. This setting can be used to tune behaviour; see
2296 lib/hashtable.c for details.
2298 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2299 - CONFIG_ENV_FLAGS_LIST_STATIC
2300 Enable validation of the values given to environment variables when
2301 calling env set. Variables can be restricted to only decimal,
2302 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2303 the variables can also be restricted to IP address or MAC address.
2305 The format of the list is:
2306 type_attribute = [s|d|x|b|i|m]
2307 access_attribute = [a|r|o|c]
2308 attributes = type_attribute[access_attribute]
2309 entry = variable_name[:attributes]
2312 The type attributes are:
2313 s - String (default)
2316 b - Boolean ([1yYtT|0nNfF])
2320 The access attributes are:
2326 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2327 Define this to a list (string) to define the ".flags"
2328 environment variable in the default or embedded environment.
2330 - CONFIG_ENV_FLAGS_LIST_STATIC
2331 Define this to a list (string) to define validation that
2332 should be done if an entry is not found in the ".flags"
2333 environment variable. To override a setting in the static
2334 list, simply add an entry for the same variable name to the
2337 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2338 regular expression. This allows multiple variables to define the same
2339 flags without explicitly listing them for each variable.
2341 The following definitions that deal with the placement and management
2342 of environment data (variable area); in general, we support the
2343 following configurations:
2345 - CONFIG_BUILD_ENVCRC:
2347 Builds up envcrc with the target environment so that external utils
2348 may easily extract it and embed it in final U-Boot images.
2350 BE CAREFUL! The first access to the environment happens quite early
2351 in U-Boot initialization (when we try to get the setting of for the
2352 console baudrate). You *MUST* have mapped your NVRAM area then, or
2355 Please note that even with NVRAM we still use a copy of the
2356 environment in RAM: we could work on NVRAM directly, but we want to
2357 keep settings there always unmodified except somebody uses "saveenv"
2358 to save the current settings.
2360 BE CAREFUL! For some special cases, the local device can not use
2361 "saveenv" command. For example, the local device will get the
2362 environment stored in a remote NOR flash by SRIO or PCIE link,
2363 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2365 - CONFIG_NAND_ENV_DST
2367 Defines address in RAM to which the nand_spl code should copy the
2368 environment. If redundant environment is used, it will be copied to
2369 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2371 Please note that the environment is read-only until the monitor
2372 has been relocated to RAM and a RAM copy of the environment has been
2373 created; also, when using EEPROM you will have to use env_get_f()
2374 until then to read environment variables.
2376 The environment is protected by a CRC32 checksum. Before the monitor
2377 is relocated into RAM, as a result of a bad CRC you will be working
2378 with the compiled-in default environment - *silently*!!! [This is
2379 necessary, because the first environment variable we need is the
2380 "baudrate" setting for the console - if we have a bad CRC, we don't
2381 have any device yet where we could complain.]
2383 Note: once the monitor has been relocated, then it will complain if
2384 the default environment is used; a new CRC is computed as soon as you
2385 use the "saveenv" command to store a valid environment.
2387 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2388 Echo the inverted Ethernet link state to the fault LED.
2390 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2391 also needs to be defined.
2393 - CONFIG_SYS_FAULT_MII_ADDR:
2394 MII address of the PHY to check for the Ethernet link state.
2396 - CONFIG_NS16550_MIN_FUNCTIONS:
2397 Define this if you desire to only have use of the NS16550_init
2398 and NS16550_putc functions for the serial driver located at
2399 drivers/serial/ns16550.c. This option is useful for saving
2400 space for already greatly restricted images, including but not
2401 limited to NAND_SPL configurations.
2403 - CONFIG_DISPLAY_BOARDINFO
2404 Display information about the board that U-Boot is running on
2405 when U-Boot starts up. The board function checkboard() is called
2408 - CONFIG_DISPLAY_BOARDINFO_LATE
2409 Similar to the previous option, but display this information
2410 later, once stdio is running and output goes to the LCD, if
2413 - CONFIG_BOARD_SIZE_LIMIT:
2414 Maximum size of the U-Boot image. When defined, the
2415 build system checks that the actual size does not
2418 Low Level (hardware related) configuration options:
2419 ---------------------------------------------------
2421 - CONFIG_SYS_CACHELINE_SIZE:
2422 Cache Line Size of the CPU.
2424 - CONFIG_SYS_CCSRBAR_DEFAULT:
2425 Default (power-on reset) physical address of CCSR on Freescale
2428 - CONFIG_SYS_CCSRBAR:
2429 Virtual address of CCSR. On a 32-bit build, this is typically
2430 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2432 - CONFIG_SYS_CCSRBAR_PHYS:
2433 Physical address of CCSR. CCSR can be relocated to a new
2434 physical address, if desired. In this case, this macro should
2435 be set to that address. Otherwise, it should be set to the
2436 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2437 is typically relocated on 36-bit builds. It is recommended
2438 that this macro be defined via the _HIGH and _LOW macros:
2440 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2441 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2443 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2444 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2445 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2446 used in assembly code, so it must not contain typecasts or
2447 integer size suffixes (e.g. "ULL").
2449 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2450 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2451 used in assembly code, so it must not contain typecasts or
2452 integer size suffixes (e.g. "ULL").
2454 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2455 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2456 forced to a value that ensures that CCSR is not relocated.
2459 Most IDE controllers were designed to be connected with PCI
2460 interface. Only few of them were designed for AHB interface.
2461 When software is doing ATA command and data transfer to
2462 IDE devices through IDE-AHB controller, some additional
2463 registers accessing to these kind of IDE-AHB controller
2466 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2467 DO NOT CHANGE unless you know exactly what you're
2468 doing! (11-4) [MPC8xx systems only]
2470 - CONFIG_SYS_INIT_RAM_ADDR:
2472 Start address of memory area that can be used for
2473 initial data and stack; please note that this must be
2474 writable memory that is working WITHOUT special
2475 initialization, i. e. you CANNOT use normal RAM which
2476 will become available only after programming the
2477 memory controller and running certain initialization
2480 U-Boot uses the following memory types:
2481 - MPC8xx: IMMR (internal memory of the CPU)
2483 - CONFIG_SYS_GBL_DATA_OFFSET:
2485 Offset of the initial data structure in the memory
2486 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2487 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2488 data is located at the end of the available space
2489 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2490 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2491 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2492 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2495 On the MPC824X (or other systems that use the data
2496 cache for initial memory) the address chosen for
2497 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2498 point to an otherwise UNUSED address space between
2499 the top of RAM and the start of the PCI space.
2501 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2503 - CONFIG_SYS_OR_TIMING_SDRAM:
2506 - CONFIG_SYS_MAMR_PTA:
2507 periodic timer for refresh
2510 Chip has SRIO or not
2513 Board has SRIO 1 port available
2516 Board has SRIO 2 port available
2518 - CONFIG_SRIO_PCIE_BOOT_MASTER
2519 Board can support master function for Boot from SRIO and PCIE
2521 - CONFIG_SYS_SRIOn_MEM_VIRT:
2522 Virtual Address of SRIO port 'n' memory region
2524 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2525 Physical Address of SRIO port 'n' memory region
2527 - CONFIG_SYS_SRIOn_MEM_SIZE:
2528 Size of SRIO port 'n' memory region
2530 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2531 Defined to tell the NAND controller that the NAND chip is using
2533 Not all NAND drivers use this symbol.
2534 Example of drivers that use it:
2535 - drivers/mtd/nand/raw/ndfc.c
2536 - drivers/mtd/nand/raw/mxc_nand.c
2538 - CONFIG_SYS_NDFC_EBC0_CFG
2539 Sets the EBC0_CFG register for the NDFC. If not defined
2540 a default value will be used.
2543 Get DDR timing information from an I2C EEPROM. Common
2544 with pluggable memory modules such as SODIMMs
2547 I2C address of the SPD EEPROM
2549 - CONFIG_SYS_SPD_BUS_NUM
2550 If SPD EEPROM is on an I2C bus other than the first
2551 one, specify here. Note that the value must resolve
2552 to something your driver can deal with.
2554 - CONFIG_SYS_DDR_RAW_TIMING
2555 Get DDR timing information from other than SPD. Common with
2556 soldered DDR chips onboard without SPD. DDR raw timing
2557 parameters are extracted from datasheet and hard-coded into
2558 header files or board specific files.
2560 - CONFIG_FSL_DDR_INTERACTIVE
2561 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2563 - CONFIG_FSL_DDR_SYNC_REFRESH
2564 Enable sync of refresh for multiple controllers.
2566 - CONFIG_FSL_DDR_BIST
2567 Enable built-in memory test for Freescale DDR controllers.
2569 - CONFIG_SYS_83XX_DDR_USES_CS0
2570 Only for 83xx systems. If specified, then DDR should
2571 be configured using CS0 and CS1 instead of CS2 and CS3.
2574 Enable RMII mode for all FECs.
2575 Note that this is a global option, we can't
2576 have one FEC in standard MII mode and another in RMII mode.
2578 - CONFIG_CRC32_VERIFY
2579 Add a verify option to the crc32 command.
2582 => crc32 -v <address> <count> <crc32>
2584 Where address/count indicate a memory area
2585 and crc32 is the correct crc32 which the
2589 Add the "loopw" memory command. This only takes effect if
2590 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2592 - CONFIG_CMD_MX_CYCLIC
2593 Add the "mdc" and "mwc" memory commands. These are cyclic
2598 This command will print 4 bytes (10,11,12,13) each 500 ms.
2600 => mwc.l 100 12345678 10
2601 This command will write 12345678 to address 100 all 10 ms.
2603 This only takes effect if the memory commands are activated
2604 globally (CONFIG_CMD_MEMORY).
2607 Set when the currently-running compilation is for an artifact
2608 that will end up in the SPL (as opposed to the TPL or U-Boot
2609 proper). Code that needs stage-specific behavior should check
2613 Set when the currently-running compilation is for an artifact
2614 that will end up in the TPL (as opposed to the SPL or U-Boot
2615 proper). Code that needs stage-specific behavior should check
2618 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2619 Only for 85xx systems. If this variable is specified, the section
2620 .resetvec is not kept and the section .bootpg is placed in the
2621 previous 4k of the .text section.
2623 - CONFIG_ARCH_MAP_SYSMEM
2624 Generally U-Boot (and in particular the md command) uses
2625 effective address. It is therefore not necessary to regard
2626 U-Boot address as virtual addresses that need to be translated
2627 to physical addresses. However, sandbox requires this, since
2628 it maintains its own little RAM buffer which contains all
2629 addressable memory. This option causes some memory accesses
2630 to be mapped through map_sysmem() / unmap_sysmem().
2632 - CONFIG_X86_RESET_VECTOR
2633 If defined, the x86 reset vector code is included. This is not
2634 needed when U-Boot is running from Coreboot.
2636 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2637 Option to disable subpage write in NAND driver
2638 driver that uses this:
2639 drivers/mtd/nand/raw/davinci_nand.c
2641 Freescale QE/FMAN Firmware Support:
2642 -----------------------------------
2644 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2645 loading of "firmware", which is encoded in the QE firmware binary format.
2646 This firmware often needs to be loaded during U-Boot booting, so macros
2647 are used to identify the storage device (NOR flash, SPI, etc) and the address
2650 - CONFIG_SYS_FMAN_FW_ADDR
2651 The address in the storage device where the FMAN microcode is located. The
2652 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2655 - CONFIG_SYS_QE_FW_ADDR
2656 The address in the storage device where the QE microcode is located. The
2657 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2660 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2661 The maximum possible size of the firmware. The firmware binary format
2662 has a field that specifies the actual size of the firmware, but it
2663 might not be possible to read any part of the firmware unless some
2664 local storage is allocated to hold the entire firmware first.
2666 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2667 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2668 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2669 virtual address in NOR flash.
2671 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2672 Specifies that QE/FMAN firmware is located in NAND flash.
2673 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2675 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2676 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2677 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2679 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2680 Specifies that QE/FMAN firmware is located in the remote (master)
2681 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2682 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2683 window->master inbound window->master LAW->the ucode address in
2684 master's memory space.
2686 Freescale Layerscape Management Complex Firmware Support:
2687 ---------------------------------------------------------
2688 The Freescale Layerscape Management Complex (MC) supports the loading of
2690 This firmware often needs to be loaded during U-Boot booting, so macros
2691 are used to identify the storage device (NOR flash, SPI, etc) and the address
2694 - CONFIG_FSL_MC_ENET
2695 Enable the MC driver for Layerscape SoCs.
2697 Freescale Layerscape Debug Server Support:
2698 -------------------------------------------
2699 The Freescale Layerscape Debug Server Support supports the loading of
2700 "Debug Server firmware" and triggering SP boot-rom.
2701 This firmware often needs to be loaded during U-Boot booting.
2703 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2704 Define alignment of reserved memory MC requires
2709 In order to achieve reproducible builds, timestamps used in the U-Boot build
2710 process have to be set to a fixed value.
2712 This is done using the SOURCE_DATE_EPOCH environment variable.
2713 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2714 option for U-Boot or an environment variable in U-Boot.
2716 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2718 Building the Software:
2719 ======================
2721 Building U-Boot has been tested in several native build environments
2722 and in many different cross environments. Of course we cannot support
2723 all possibly existing versions of cross development tools in all
2724 (potentially obsolete) versions. In case of tool chain problems we
2725 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2726 which is extensively used to build and test U-Boot.
2728 If you are not using a native environment, it is assumed that you
2729 have GNU cross compiling tools available in your path. In this case,
2730 you must set the environment variable CROSS_COMPILE in your shell.
2731 Note that no changes to the Makefile or any other source files are
2732 necessary. For example using the ELDK on a 4xx CPU, please enter:
2734 $ CROSS_COMPILE=ppc_4xx-
2735 $ export CROSS_COMPILE
2737 U-Boot is intended to be simple to build. After installing the
2738 sources you must configure U-Boot for one specific board type. This
2743 where "NAME_defconfig" is the name of one of the existing configu-
2744 rations; see configs/*_defconfig for supported names.
2746 Note: for some boards special configuration names may exist; check if
2747 additional information is available from the board vendor; for
2748 instance, the TQM823L systems are available without (standard)
2749 or with LCD support. You can select such additional "features"
2750 when choosing the configuration, i. e.
2752 make TQM823L_defconfig
2753 - will configure for a plain TQM823L, i. e. no LCD support
2755 make TQM823L_LCD_defconfig
2756 - will configure for a TQM823L with U-Boot console on LCD
2761 Finally, type "make all", and you should get some working U-Boot
2762 images ready for download to / installation on your system:
2764 - "u-boot.bin" is a raw binary image
2765 - "u-boot" is an image in ELF binary format
2766 - "u-boot.srec" is in Motorola S-Record format
2768 By default the build is performed locally and the objects are saved
2769 in the source directory. One of the two methods can be used to change
2770 this behavior and build U-Boot to some external directory:
2772 1. Add O= to the make command line invocations:
2774 make O=/tmp/build distclean
2775 make O=/tmp/build NAME_defconfig
2776 make O=/tmp/build all
2778 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2780 export KBUILD_OUTPUT=/tmp/build
2785 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2788 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2789 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2790 For example to treat all compiler warnings as errors:
2792 make KCFLAGS=-Werror
2794 Please be aware that the Makefiles assume you are using GNU make, so
2795 for instance on NetBSD you might need to use "gmake" instead of
2799 If the system board that you have is not listed, then you will need
2800 to port U-Boot to your hardware platform. To do this, follow these
2803 1. Create a new directory to hold your board specific code. Add any
2804 files you need. In your board directory, you will need at least
2805 the "Makefile" and a "<board>.c".
2806 2. Create a new configuration file "include/configs/<board>.h" for
2808 3. If you're porting U-Boot to a new CPU, then also create a new
2809 directory to hold your CPU specific code. Add any files you need.
2810 4. Run "make <board>_defconfig" with your new name.
2811 5. Type "make", and you should get a working "u-boot.srec" file
2812 to be installed on your target system.
2813 6. Debug and solve any problems that might arise.
2814 [Of course, this last step is much harder than it sounds.]
2817 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2818 ==============================================================
2820 If you have modified U-Boot sources (for instance added a new board
2821 or support for new devices, a new CPU, etc.) you are expected to
2822 provide feedback to the other developers. The feedback normally takes
2823 the form of a "patch", i.e. a context diff against a certain (latest
2824 official or latest in the git repository) version of U-Boot sources.
2826 But before you submit such a patch, please verify that your modifi-
2827 cation did not break existing code. At least make sure that *ALL* of
2828 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2829 just run the buildman script (tools/buildman/buildman), which will
2830 configure and build U-Boot for ALL supported system. Be warned, this
2831 will take a while. Please see the buildman README, or run 'buildman -H'
2835 See also "U-Boot Porting Guide" below.
2838 Monitor Commands - Overview:
2839 ============================
2841 go - start application at address 'addr'
2842 run - run commands in an environment variable
2843 bootm - boot application image from memory
2844 bootp - boot image via network using BootP/TFTP protocol
2845 bootz - boot zImage from memory
2846 tftpboot- boot image via network using TFTP protocol
2847 and env variables "ipaddr" and "serverip"
2848 (and eventually "gatewayip")
2849 tftpput - upload a file via network using TFTP protocol
2850 rarpboot- boot image via network using RARP/TFTP protocol
2851 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2852 loads - load S-Record file over serial line
2853 loadb - load binary file over serial line (kermit mode)
2855 mm - memory modify (auto-incrementing)
2856 nm - memory modify (constant address)
2857 mw - memory write (fill)
2860 cmp - memory compare
2861 crc32 - checksum calculation
2862 i2c - I2C sub-system
2863 sspi - SPI utility commands
2864 base - print or set address offset
2865 printenv- print environment variables
2866 pwm - control pwm channels
2867 setenv - set environment variables
2868 saveenv - save environment variables to persistent storage
2869 protect - enable or disable FLASH write protection
2870 erase - erase FLASH memory
2871 flinfo - print FLASH memory information
2872 nand - NAND memory operations (see doc/README.nand)
2873 bdinfo - print Board Info structure
2874 iminfo - print header information for application image
2875 coninfo - print console devices and informations
2876 ide - IDE sub-system
2877 loop - infinite loop on address range
2878 loopw - infinite write loop on address range
2879 mtest - simple RAM test
2880 icache - enable or disable instruction cache
2881 dcache - enable or disable data cache
2882 reset - Perform RESET of the CPU
2883 echo - echo args to console
2884 version - print monitor version
2885 help - print online help
2886 ? - alias for 'help'
2889 Monitor Commands - Detailed Description:
2890 ========================================
2894 For now: just type "help <command>".
2897 Note for Redundant Ethernet Interfaces:
2898 =======================================
2900 Some boards come with redundant Ethernet interfaces; U-Boot supports
2901 such configurations and is capable of automatic selection of a
2902 "working" interface when needed. MAC assignment works as follows:
2904 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2905 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2906 "eth1addr" (=>eth1), "eth2addr", ...
2908 If the network interface stores some valid MAC address (for instance
2909 in SROM), this is used as default address if there is NO correspon-
2910 ding setting in the environment; if the corresponding environment
2911 variable is set, this overrides the settings in the card; that means:
2913 o If the SROM has a valid MAC address, and there is no address in the
2914 environment, the SROM's address is used.
2916 o If there is no valid address in the SROM, and a definition in the
2917 environment exists, then the value from the environment variable is
2920 o If both the SROM and the environment contain a MAC address, and
2921 both addresses are the same, this MAC address is used.
2923 o If both the SROM and the environment contain a MAC address, and the
2924 addresses differ, the value from the environment is used and a
2927 o If neither SROM nor the environment contain a MAC address, an error
2928 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2929 a random, locally-assigned MAC is used.
2931 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2932 will be programmed into hardware as part of the initialization process. This
2933 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2934 The naming convention is as follows:
2935 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2940 U-Boot is capable of booting (and performing other auxiliary operations on)
2941 images in two formats:
2943 New uImage format (FIT)
2944 -----------------------
2946 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2947 to Flattened Device Tree). It allows the use of images with multiple
2948 components (several kernels, ramdisks, etc.), with contents protected by
2949 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2955 Old image format is based on binary files which can be basically anything,
2956 preceded by a special header; see the definitions in include/image.h for
2957 details; basically, the header defines the following image properties:
2959 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2960 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2961 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2962 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
2964 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2965 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2966 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2967 * Compression Type (uncompressed, gzip, bzip2)
2973 The header is marked by a special Magic Number, and both the header
2974 and the data portions of the image are secured against corruption by
2981 Although U-Boot should support any OS or standalone application
2982 easily, the main focus has always been on Linux during the design of
2985 U-Boot includes many features that so far have been part of some
2986 special "boot loader" code within the Linux kernel. Also, any
2987 "initrd" images to be used are no longer part of one big Linux image;
2988 instead, kernel and "initrd" are separate images. This implementation
2989 serves several purposes:
2991 - the same features can be used for other OS or standalone
2992 applications (for instance: using compressed images to reduce the
2993 Flash memory footprint)
2995 - it becomes much easier to port new Linux kernel versions because
2996 lots of low-level, hardware dependent stuff are done by U-Boot
2998 - the same Linux kernel image can now be used with different "initrd"
2999 images; of course this also means that different kernel images can
3000 be run with the same "initrd". This makes testing easier (you don't
3001 have to build a new "zImage.initrd" Linux image when you just
3002 change a file in your "initrd"). Also, a field-upgrade of the
3003 software is easier now.
3009 Porting Linux to U-Boot based systems:
3010 ---------------------------------------
3012 U-Boot cannot save you from doing all the necessary modifications to
3013 configure the Linux device drivers for use with your target hardware
3014 (no, we don't intend to provide a full virtual machine interface to
3017 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
3019 Just make sure your machine specific header file (for instance
3020 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3021 Information structure as we define in include/asm-<arch>/u-boot.h,
3022 and make sure that your definition of IMAP_ADDR uses the same value
3023 as your U-Boot configuration in CONFIG_SYS_IMMR.
3025 Note that U-Boot now has a driver model, a unified model for drivers.
3026 If you are adding a new driver, plumb it into driver model. If there
3027 is no uclass available, you are encouraged to create one. See
3031 Configuring the Linux kernel:
3032 -----------------------------
3034 No specific requirements for U-Boot. Make sure you have some root
3035 device (initial ramdisk, NFS) for your target system.
3038 Building a Linux Image:
3039 -----------------------
3041 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3042 not used. If you use recent kernel source, a new build target
3043 "uImage" will exist which automatically builds an image usable by
3044 U-Boot. Most older kernels also have support for a "pImage" target,
3045 which was introduced for our predecessor project PPCBoot and uses a
3046 100% compatible format.
3050 make TQM850L_defconfig
3055 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3056 encapsulate a compressed Linux kernel image with header information,
3057 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3059 * build a standard "vmlinux" kernel image (in ELF binary format):
3061 * convert the kernel into a raw binary image:
3063 ${CROSS_COMPILE}-objcopy -O binary \
3064 -R .note -R .comment \
3065 -S vmlinux linux.bin
3067 * compress the binary image:
3071 * package compressed binary image for U-Boot:
3073 mkimage -A ppc -O linux -T kernel -C gzip \
3074 -a 0 -e 0 -n "Linux Kernel Image" \
3075 -d linux.bin.gz uImage
3078 The "mkimage" tool can also be used to create ramdisk images for use
3079 with U-Boot, either separated from the Linux kernel image, or
3080 combined into one file. "mkimage" encapsulates the images with a 64
3081 byte header containing information about target architecture,
3082 operating system, image type, compression method, entry points, time
3083 stamp, CRC32 checksums, etc.
3085 "mkimage" can be called in two ways: to verify existing images and
3086 print the header information, or to build new images.
3088 In the first form (with "-l" option) mkimage lists the information
3089 contained in the header of an existing U-Boot image; this includes
3090 checksum verification:
3092 tools/mkimage -l image
3093 -l ==> list image header information
3095 The second form (with "-d" option) is used to build a U-Boot image
3096 from a "data file" which is used as image payload:
3098 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3099 -n name -d data_file image
3100 -A ==> set architecture to 'arch'
3101 -O ==> set operating system to 'os'
3102 -T ==> set image type to 'type'
3103 -C ==> set compression type 'comp'
3104 -a ==> set load address to 'addr' (hex)
3105 -e ==> set entry point to 'ep' (hex)
3106 -n ==> set image name to 'name'
3107 -d ==> use image data from 'datafile'
3109 Right now, all Linux kernels for PowerPC systems use the same load
3110 address (0x00000000), but the entry point address depends on the
3113 - 2.2.x kernels have the entry point at 0x0000000C,
3114 - 2.3.x and later kernels have the entry point at 0x00000000.
3116 So a typical call to build a U-Boot image would read:
3118 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3119 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3120 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
3121 > examples/uImage.TQM850L
3122 Image Name: 2.4.4 kernel for TQM850L
3123 Created: Wed Jul 19 02:34:59 2000
3124 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3125 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3126 Load Address: 0x00000000
3127 Entry Point: 0x00000000
3129 To verify the contents of the image (or check for corruption):
3131 -> tools/mkimage -l examples/uImage.TQM850L
3132 Image Name: 2.4.4 kernel for TQM850L
3133 Created: Wed Jul 19 02:34:59 2000
3134 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3135 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3136 Load Address: 0x00000000
3137 Entry Point: 0x00000000
3139 NOTE: for embedded systems where boot time is critical you can trade
3140 speed for memory and install an UNCOMPRESSED image instead: this
3141 needs more space in Flash, but boots much faster since it does not
3142 need to be uncompressed:
3144 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
3145 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3146 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3147 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
3148 > examples/uImage.TQM850L-uncompressed
3149 Image Name: 2.4.4 kernel for TQM850L
3150 Created: Wed Jul 19 02:34:59 2000
3151 Image Type: PowerPC Linux Kernel Image (uncompressed)
3152 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3153 Load Address: 0x00000000
3154 Entry Point: 0x00000000
3157 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3158 when your kernel is intended to use an initial ramdisk:
3160 -> tools/mkimage -n 'Simple Ramdisk Image' \
3161 > -A ppc -O linux -T ramdisk -C gzip \
3162 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3163 Image Name: Simple Ramdisk Image
3164 Created: Wed Jan 12 14:01:50 2000
3165 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3166 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3167 Load Address: 0x00000000
3168 Entry Point: 0x00000000
3170 The "dumpimage" tool can be used to disassemble or list the contents of images
3171 built by mkimage. See dumpimage's help output (-h) for details.
3173 Installing a Linux Image:
3174 -------------------------
3176 To downloading a U-Boot image over the serial (console) interface,
3177 you must convert the image to S-Record format:
3179 objcopy -I binary -O srec examples/image examples/image.srec
3181 The 'objcopy' does not understand the information in the U-Boot
3182 image header, so the resulting S-Record file will be relative to
3183 address 0x00000000. To load it to a given address, you need to
3184 specify the target address as 'offset' parameter with the 'loads'
3187 Example: install the image to address 0x40100000 (which on the
3188 TQM8xxL is in the first Flash bank):
3190 => erase 40100000 401FFFFF
3196 ## Ready for S-Record download ...
3197 ~>examples/image.srec
3198 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3200 15989 15990 15991 15992
3201 [file transfer complete]
3203 ## Start Addr = 0x00000000
3206 You can check the success of the download using the 'iminfo' command;
3207 this includes a checksum verification so you can be sure no data
3208 corruption happened:
3212 ## Checking Image at 40100000 ...
3213 Image Name: 2.2.13 for initrd on TQM850L
3214 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3215 Data Size: 335725 Bytes = 327 kB = 0 MB
3216 Load Address: 00000000
3217 Entry Point: 0000000c
3218 Verifying Checksum ... OK
3224 The "bootm" command is used to boot an application that is stored in
3225 memory (RAM or Flash). In case of a Linux kernel image, the contents
3226 of the "bootargs" environment variable is passed to the kernel as
3227 parameters. You can check and modify this variable using the
3228 "printenv" and "setenv" commands:
3231 => printenv bootargs
3232 bootargs=root=/dev/ram
3234 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3236 => printenv bootargs
3237 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3240 ## Booting Linux kernel at 40020000 ...
3241 Image Name: 2.2.13 for NFS on TQM850L
3242 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3243 Data Size: 381681 Bytes = 372 kB = 0 MB
3244 Load Address: 00000000
3245 Entry Point: 0000000c
3246 Verifying Checksum ... OK
3247 Uncompressing Kernel Image ... OK
3248 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
3249 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3250 time_init: decrementer frequency = 187500000/60
3251 Calibrating delay loop... 49.77 BogoMIPS
3252 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3255 If you want to boot a Linux kernel with initial RAM disk, you pass
3256 the memory addresses of both the kernel and the initrd image (PPBCOOT
3257 format!) to the "bootm" command:
3259 => imi 40100000 40200000
3261 ## Checking Image at 40100000 ...
3262 Image Name: 2.2.13 for initrd on TQM850L
3263 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3264 Data Size: 335725 Bytes = 327 kB = 0 MB
3265 Load Address: 00000000
3266 Entry Point: 0000000c
3267 Verifying Checksum ... OK
3269 ## Checking Image at 40200000 ...
3270 Image Name: Simple Ramdisk Image
3271 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3272 Data Size: 566530 Bytes = 553 kB = 0 MB
3273 Load Address: 00000000
3274 Entry Point: 00000000
3275 Verifying Checksum ... OK
3277 => bootm 40100000 40200000
3278 ## Booting Linux kernel at 40100000 ...
3279 Image Name: 2.2.13 for initrd on TQM850L
3280 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3281 Data Size: 335725 Bytes = 327 kB = 0 MB
3282 Load Address: 00000000
3283 Entry Point: 0000000c
3284 Verifying Checksum ... OK
3285 Uncompressing Kernel Image ... OK
3286 ## Loading RAMDisk Image at 40200000 ...
3287 Image Name: Simple Ramdisk Image
3288 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3289 Data Size: 566530 Bytes = 553 kB = 0 MB
3290 Load Address: 00000000
3291 Entry Point: 00000000
3292 Verifying Checksum ... OK
3293 Loading Ramdisk ... OK
3294 Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
3295 Boot arguments: root=/dev/ram
3296 time_init: decrementer frequency = 187500000/60
3297 Calibrating delay loop... 49.77 BogoMIPS
3299 RAMDISK: Compressed image found at block 0
3300 VFS: Mounted root (ext2 filesystem).
3304 Boot Linux and pass a flat device tree:
3307 First, U-Boot must be compiled with the appropriate defines. See the section
3308 titled "Linux Kernel Interface" above for a more in depth explanation. The
3309 following is an example of how to start a kernel and pass an updated
3315 oft=oftrees/mpc8540ads.dtb
3316 => tftp $oftaddr $oft
3317 Speed: 1000, full duplex
3319 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3320 Filename 'oftrees/mpc8540ads.dtb'.
3321 Load address: 0x300000
3324 Bytes transferred = 4106 (100a hex)
3325 => tftp $loadaddr $bootfile
3326 Speed: 1000, full duplex
3328 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3330 Load address: 0x200000
3331 Loading:############
3333 Bytes transferred = 1029407 (fb51f hex)
3338 => bootm $loadaddr - $oftaddr
3339 ## Booting image at 00200000 ...
3340 Image Name: Linux-2.6.17-dirty
3341 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3342 Data Size: 1029343 Bytes = 1005.2 kB
3343 Load Address: 00000000
3344 Entry Point: 00000000
3345 Verifying Checksum ... OK
3346 Uncompressing Kernel Image ... OK
3347 Booting using flat device tree at 0x300000
3348 Using MPC85xx ADS machine description
3349 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3353 More About U-Boot Image Types:
3354 ------------------------------
3356 U-Boot supports the following image types:
3358 "Standalone Programs" are directly runnable in the environment
3359 provided by U-Boot; it is expected that (if they behave
3360 well) you can continue to work in U-Boot after return from
3361 the Standalone Program.
3362 "OS Kernel Images" are usually images of some Embedded OS which
3363 will take over control completely. Usually these programs
3364 will install their own set of exception handlers, device
3365 drivers, set up the MMU, etc. - this means, that you cannot
3366 expect to re-enter U-Boot except by resetting the CPU.
3367 "RAMDisk Images" are more or less just data blocks, and their
3368 parameters (address, size) are passed to an OS kernel that is
3370 "Multi-File Images" contain several images, typically an OS
3371 (Linux) kernel image and one or more data images like
3372 RAMDisks. This construct is useful for instance when you want
3373 to boot over the network using BOOTP etc., where the boot
3374 server provides just a single image file, but you want to get
3375 for instance an OS kernel and a RAMDisk image.
3377 "Multi-File Images" start with a list of image sizes, each
3378 image size (in bytes) specified by an "uint32_t" in network
3379 byte order. This list is terminated by an "(uint32_t)0".
3380 Immediately after the terminating 0 follow the images, one by
3381 one, all aligned on "uint32_t" boundaries (size rounded up to
3382 a multiple of 4 bytes).
3384 "Firmware Images" are binary images containing firmware (like
3385 U-Boot or FPGA images) which usually will be programmed to
3388 "Script files" are command sequences that will be executed by
3389 U-Boot's command interpreter; this feature is especially
3390 useful when you configure U-Boot to use a real shell (hush)
3391 as command interpreter.
3393 Booting the Linux zImage:
3394 -------------------------
3396 On some platforms, it's possible to boot Linux zImage. This is done
3397 using the "bootz" command. The syntax of "bootz" command is the same
3398 as the syntax of "bootm" command.
3400 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3401 kernel with raw initrd images. The syntax is slightly different, the
3402 address of the initrd must be augmented by it's size, in the following
3403 format: "<initrd addres>:<initrd size>".
3409 One of the features of U-Boot is that you can dynamically load and
3410 run "standalone" applications, which can use some resources of
3411 U-Boot like console I/O functions or interrupt services.
3413 Two simple examples are included with the sources:
3418 'examples/hello_world.c' contains a small "Hello World" Demo
3419 application; it is automatically compiled when you build U-Boot.
3420 It's configured to run at address 0x00040004, so you can play with it
3424 ## Ready for S-Record download ...
3425 ~>examples/hello_world.srec
3426 1 2 3 4 5 6 7 8 9 10 11 ...
3427 [file transfer complete]
3429 ## Start Addr = 0x00040004
3431 => go 40004 Hello World! This is a test.
3432 ## Starting application at 0x00040004 ...
3443 Hit any key to exit ...
3445 ## Application terminated, rc = 0x0
3447 Another example, which demonstrates how to register a CPM interrupt
3448 handler with the U-Boot code, can be found in 'examples/timer.c'.
3449 Here, a CPM timer is set up to generate an interrupt every second.
3450 The interrupt service routine is trivial, just printing a '.'
3451 character, but this is just a demo program. The application can be
3452 controlled by the following keys:
3454 ? - print current values og the CPM Timer registers
3455 b - enable interrupts and start timer
3456 e - stop timer and disable interrupts
3457 q - quit application
3460 ## Ready for S-Record download ...
3461 ~>examples/timer.srec
3462 1 2 3 4 5 6 7 8 9 10 11 ...
3463 [file transfer complete]
3465 ## Start Addr = 0x00040004
3468 ## Starting application at 0x00040004 ...
3471 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3474 [q, b, e, ?] Set interval 1000000 us
3477 [q, b, e, ?] ........
3478 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3481 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3484 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3487 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3489 [q, b, e, ?] ...Stopping timer
3491 [q, b, e, ?] ## Application terminated, rc = 0x0
3497 Over time, many people have reported problems when trying to use the
3498 "minicom" terminal emulation program for serial download. I (wd)
3499 consider minicom to be broken, and recommend not to use it. Under
3500 Unix, I recommend to use C-Kermit for general purpose use (and
3501 especially for kermit binary protocol download ("loadb" command), and
3502 use "cu" for S-Record download ("loads" command). See
3503 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3504 for help with kermit.
3507 Nevertheless, if you absolutely want to use it try adding this
3508 configuration to your "File transfer protocols" section:
3510 Name Program Name U/D FullScr IO-Red. Multi
3511 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3512 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3518 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3519 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3521 Building requires a cross environment; it is known to work on
3522 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3523 need gmake since the Makefiles are not compatible with BSD make).
3524 Note that the cross-powerpc package does not install include files;
3525 attempting to build U-Boot will fail because <machine/ansi.h> is
3526 missing. This file has to be installed and patched manually:
3528 # cd /usr/pkg/cross/powerpc-netbsd/include
3530 # ln -s powerpc machine
3531 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3532 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3534 Native builds *don't* work due to incompatibilities between native
3535 and U-Boot include files.
3537 Booting assumes that (the first part of) the image booted is a
3538 stage-2 loader which in turn loads and then invokes the kernel
3539 proper. Loader sources will eventually appear in the NetBSD source
3540 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3541 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3544 Implementation Internals:
3545 =========================
3547 The following is not intended to be a complete description of every
3548 implementation detail. However, it should help to understand the
3549 inner workings of U-Boot and make it easier to port it to custom
3553 Initial Stack, Global Data:
3554 ---------------------------
3556 The implementation of U-Boot is complicated by the fact that U-Boot
3557 starts running out of ROM (flash memory), usually without access to
3558 system RAM (because the memory controller is not initialized yet).
3559 This means that we don't have writable Data or BSS segments, and BSS
3560 is not initialized as zero. To be able to get a C environment working
3561 at all, we have to allocate at least a minimal stack. Implementation
3562 options for this are defined and restricted by the CPU used: Some CPU
3563 models provide on-chip memory (like the IMMR area on MPC8xx and
3564 MPC826x processors), on others (parts of) the data cache can be
3565 locked as (mis-) used as memory, etc.
3567 Chris Hallinan posted a good summary of these issues to the
3568 U-Boot mailing list:
3570 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3571 From: "Chris Hallinan" <clh@net1plus.com>
3572 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3575 Correct me if I'm wrong, folks, but the way I understand it
3576 is this: Using DCACHE as initial RAM for Stack, etc, does not
3577 require any physical RAM backing up the cache. The cleverness
3578 is that the cache is being used as a temporary supply of
3579 necessary storage before the SDRAM controller is setup. It's
3580 beyond the scope of this list to explain the details, but you
3581 can see how this works by studying the cache architecture and
3582 operation in the architecture and processor-specific manuals.
3584 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3585 is another option for the system designer to use as an
3586 initial stack/RAM area prior to SDRAM being available. Either
3587 option should work for you. Using CS 4 should be fine if your
3588 board designers haven't used it for something that would
3589 cause you grief during the initial boot! It is frequently not
3592 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3593 with your processor/board/system design. The default value
3594 you will find in any recent u-boot distribution in
3595 walnut.h should work for you. I'd set it to a value larger
3596 than your SDRAM module. If you have a 64MB SDRAM module, set
3597 it above 400_0000. Just make sure your board has no resources
3598 that are supposed to respond to that address! That code in
3599 start.S has been around a while and should work as is when
3600 you get the config right.
3605 It is essential to remember this, since it has some impact on the C
3606 code for the initialization procedures:
3608 * Initialized global data (data segment) is read-only. Do not attempt
3611 * Do not use any uninitialized global data (or implicitly initialized
3612 as zero data - BSS segment) at all - this is undefined, initiali-
3613 zation is performed later (when relocating to RAM).
3615 * Stack space is very limited. Avoid big data buffers or things like
3618 Having only the stack as writable memory limits means we cannot use
3619 normal global data to share information between the code. But it
3620 turned out that the implementation of U-Boot can be greatly
3621 simplified by making a global data structure (gd_t) available to all
3622 functions. We could pass a pointer to this data as argument to _all_
3623 functions, but this would bloat the code. Instead we use a feature of
3624 the GCC compiler (Global Register Variables) to share the data: we
3625 place a pointer (gd) to the global data into a register which we
3626 reserve for this purpose.
3628 When choosing a register for such a purpose we are restricted by the
3629 relevant (E)ABI specifications for the current architecture, and by
3630 GCC's implementation.
3632 For PowerPC, the following registers have specific use:
3634 R2: reserved for system use
3635 R3-R4: parameter passing and return values
3636 R5-R10: parameter passing
3637 R13: small data area pointer
3641 (U-Boot also uses R12 as internal GOT pointer. r12
3642 is a volatile register so r12 needs to be reset when
3643 going back and forth between asm and C)
3645 ==> U-Boot will use R2 to hold a pointer to the global data
3647 Note: on PPC, we could use a static initializer (since the
3648 address of the global data structure is known at compile time),
3649 but it turned out that reserving a register results in somewhat
3650 smaller code - although the code savings are not that big (on
3651 average for all boards 752 bytes for the whole U-Boot image,
3652 624 text + 127 data).
3654 On ARM, the following registers are used:
3656 R0: function argument word/integer result
3657 R1-R3: function argument word
3658 R9: platform specific
3659 R10: stack limit (used only if stack checking is enabled)
3660 R11: argument (frame) pointer
3661 R12: temporary workspace
3664 R15: program counter
3666 ==> U-Boot will use R9 to hold a pointer to the global data
3668 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3670 On Nios II, the ABI is documented here:
3671 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3673 ==> U-Boot will use gp to hold a pointer to the global data
3675 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3676 to access small data sections, so gp is free.
3678 On NDS32, the following registers are used:
3680 R0-R1: argument/return
3682 R15: temporary register for assembler
3683 R16: trampoline register
3684 R28: frame pointer (FP)
3685 R29: global pointer (GP)
3686 R30: link register (LP)
3687 R31: stack pointer (SP)
3688 PC: program counter (PC)
3690 ==> U-Boot will use R10 to hold a pointer to the global data
3692 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3693 or current versions of GCC may "optimize" the code too much.
3695 On RISC-V, the following registers are used:
3697 x0: hard-wired zero (zero)
3698 x1: return address (ra)
3699 x2: stack pointer (sp)
3700 x3: global pointer (gp)
3701 x4: thread pointer (tp)
3702 x5: link register (t0)
3703 x8: frame pointer (fp)
3704 x10-x11: arguments/return values (a0-1)
3705 x12-x17: arguments (a2-7)
3706 x28-31: temporaries (t3-6)
3707 pc: program counter (pc)
3709 ==> U-Boot will use gp to hold a pointer to the global data
3714 U-Boot runs in system state and uses physical addresses, i.e. the
3715 MMU is not used either for address mapping nor for memory protection.
3717 The available memory is mapped to fixed addresses using the memory
3718 controller. In this process, a contiguous block is formed for each
3719 memory type (Flash, SDRAM, SRAM), even when it consists of several
3720 physical memory banks.
3722 U-Boot is installed in the first 128 kB of the first Flash bank (on
3723 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3724 booting and sizing and initializing DRAM, the code relocates itself
3725 to the upper end of DRAM. Immediately below the U-Boot code some
3726 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3727 configuration setting]. Below that, a structure with global Board
3728 Info data is placed, followed by the stack (growing downward).
3730 Additionally, some exception handler code is copied to the low 8 kB
3731 of DRAM (0x00000000 ... 0x00001FFF).
3733 So a typical memory configuration with 16 MB of DRAM could look like
3736 0x0000 0000 Exception Vector code
3739 0x0000 2000 Free for Application Use
3745 0x00FB FF20 Monitor Stack (Growing downward)
3746 0x00FB FFAC Board Info Data and permanent copy of global data
3747 0x00FC 0000 Malloc Arena
3750 0x00FE 0000 RAM Copy of Monitor Code
3751 ... eventually: LCD or video framebuffer
3752 ... eventually: pRAM (Protected RAM - unchanged by reset)
3753 0x00FF FFFF [End of RAM]
3756 System Initialization:
3757 ----------------------
3759 In the reset configuration, U-Boot starts at the reset entry point
3760 (on most PowerPC systems at address 0x00000100). Because of the reset
3761 configuration for CS0# this is a mirror of the on board Flash memory.
3762 To be able to re-map memory U-Boot then jumps to its link address.
3763 To be able to implement the initialization code in C, a (small!)
3764 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3765 which provide such a feature like), or in a locked part of the data
3766 cache. After that, U-Boot initializes the CPU core, the caches and
3769 Next, all (potentially) available memory banks are mapped using a
3770 preliminary mapping. For example, we put them on 512 MB boundaries
3771 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3772 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3773 programmed for SDRAM access. Using the temporary configuration, a
3774 simple memory test is run that determines the size of the SDRAM
3777 When there is more than one SDRAM bank, and the banks are of
3778 different size, the largest is mapped first. For equal size, the first
3779 bank (CS2#) is mapped first. The first mapping is always for address
3780 0x00000000, with any additional banks following immediately to create
3781 contiguous memory starting from 0.
3783 Then, the monitor installs itself at the upper end of the SDRAM area
3784 and allocates memory for use by malloc() and for the global Board
3785 Info data; also, the exception vector code is copied to the low RAM
3786 pages, and the final stack is set up.
3788 Only after this relocation will you have a "normal" C environment;
3789 until that you are restricted in several ways, mostly because you are
3790 running from ROM, and because the code will have to be relocated to a
3794 U-Boot Porting Guide:
3795 ----------------------
3797 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3801 int main(int argc, char *argv[])
3803 sighandler_t no_more_time;
3805 signal(SIGALRM, no_more_time);
3806 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3808 if (available_money > available_manpower) {
3809 Pay consultant to port U-Boot;
3813 Download latest U-Boot source;
3815 Subscribe to u-boot mailing list;
3818 email("Hi, I am new to U-Boot, how do I get started?");
3821 Read the README file in the top level directory;
3822 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3823 Read applicable doc/README.*;
3824 Read the source, Luke;
3825 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3828 if (available_money > toLocalCurrency ($2500))
3831 Add a lot of aggravation and time;
3833 if (a similar board exists) { /* hopefully... */
3834 cp -a board/<similar> board/<myboard>
3835 cp include/configs/<similar>.h include/configs/<myboard>.h
3837 Create your own board support subdirectory;
3838 Create your own board include/configs/<myboard>.h file;
3840 Edit new board/<myboard> files
3841 Edit new include/configs/<myboard>.h
3846 Add / modify source code;
3850 email("Hi, I am having problems...");
3852 Send patch file to the U-Boot email list;
3853 if (reasonable critiques)
3854 Incorporate improvements from email list code review;
3856 Defend code as written;
3862 void no_more_time (int sig)
3871 All contributions to U-Boot should conform to the Linux kernel
3872 coding style; see the kernel coding style guide at
3873 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3874 script "scripts/Lindent" in your Linux kernel source directory.
3876 Source files originating from a different project (for example the
3877 MTD subsystem) are generally exempt from these guidelines and are not
3878 reformatted to ease subsequent migration to newer versions of those
3881 Please note that U-Boot is implemented in C (and to some small parts in
3882 Assembler); no C++ is used, so please do not use C++ style comments (//)
3885 Please also stick to the following formatting rules:
3886 - remove any trailing white space
3887 - use TAB characters for indentation and vertical alignment, not spaces
3888 - make sure NOT to use DOS '\r\n' line feeds
3889 - do not add more than 2 consecutive empty lines to source files
3890 - do not add trailing empty lines to source files
3892 Submissions which do not conform to the standards may be returned
3893 with a request to reformat the changes.
3899 Since the number of patches for U-Boot is growing, we need to
3900 establish some rules. Submissions which do not conform to these rules
3901 may be rejected, even when they contain important and valuable stuff.
3903 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3905 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3906 see https://lists.denx.de/listinfo/u-boot
3908 When you send a patch, please include the following information with
3911 * For bug fixes: a description of the bug and how your patch fixes
3912 this bug. Please try to include a way of demonstrating that the
3913 patch actually fixes something.
3915 * For new features: a description of the feature and your
3918 * For major contributions, add a MAINTAINERS file with your
3919 information and associated file and directory references.
3921 * When you add support for a new board, don't forget to add a
3922 maintainer e-mail address to the boards.cfg file, too.
3924 * If your patch adds new configuration options, don't forget to
3925 document these in the README file.
3927 * The patch itself. If you are using git (which is *strongly*
3928 recommended) you can easily generate the patch using the
3929 "git format-patch". If you then use "git send-email" to send it to
3930 the U-Boot mailing list, you will avoid most of the common problems
3931 with some other mail clients.
3933 If you cannot use git, use "diff -purN OLD NEW". If your version of
3934 diff does not support these options, then get the latest version of
3937 The current directory when running this command shall be the parent
3938 directory of the U-Boot source tree (i. e. please make sure that
3939 your patch includes sufficient directory information for the
3942 We prefer patches as plain text. MIME attachments are discouraged,
3943 and compressed attachments must not be used.
3945 * If one logical set of modifications affects or creates several
3946 files, all these changes shall be submitted in a SINGLE patch file.
3948 * Changesets that contain different, unrelated modifications shall be
3949 submitted as SEPARATE patches, one patch per changeset.
3954 * Before sending the patch, run the buildman script on your patched
3955 source tree and make sure that no errors or warnings are reported
3956 for any of the boards.
3958 * Keep your modifications to the necessary minimum: A patch
3959 containing several unrelated changes or arbitrary reformats will be
3960 returned with a request to re-formatting / split it.
3962 * If you modify existing code, make sure that your new code does not
3963 add to the memory footprint of the code ;-) Small is beautiful!
3964 When adding new features, these should compile conditionally only
3965 (using #ifdef), and the resulting code with the new feature
3966 disabled must not need more memory than the old code without your
3969 * Remember that there is a size limit of 100 kB per message on the
3970 u-boot mailing list. Bigger patches will be moderated. If they are
3971 reasonable and not too big, they will be acknowledged. But patches
3972 bigger than the size limit should be avoided.