generic source base.
To enable this feature, add CONFIG_OF_CONTROL to your board config file.
-It is currently supported on ARM, x86 and Microblaze - other architectures
-will need to add code to their arch/xxx/lib/board.c file to locate the
-FDT. Alternatively you can enable generic board support on your board
-(with CONFIG_SYS_GENERIC_BOARD) if this is available (as it is for
-PowerPC). For ARM, Tegra and Exynos5 have device trees available for
-common devices.
What is a Flat Device Tree?
To use this feature you will need to get the device tree compiler here:
- git://jdl.com/software/dtc.git
+ git://git.kernel.org/pub/scm/utils/dtc/dtc.git
For example:
- $ git clone git://jdl.com/software/dtc.git
+ $ git clone git://git.kernel.org/pub/scm/utils/dtc/dtc.git
$ cd dtc
$ make
$ sudo make install
board/<vendor>/dts/<name>.dts
This should include your CPU or SOC's device tree file, placed in
-arch/<arch>/dts, and then make any adjustments required. The name of this
-is CONFIG_ARCH_DEVICE_TREE.dts.
+arch/<arch>/dts, and then make any adjustments required.
If CONFIG_OF_EMBED is defined, then it will be picked up and built into
-the U-Boot image (including u-boot.bin).
+the U-Boot image (including u-boot.bin). This is suitable for debugging
+and development only and is not recommended for production devices.
If CONFIG_OF_SEPARATE is defined, then it will be built and placed in
a u-boot.dtb file alongside u-boot.bin. A common approach is then to
cat u-boot.bin u-boot.dtb >image.bin
-and then flash image.bin onto your board.
+and then flash image.bin onto your board. Note that U-Boot creates
+u-boot-dtb.bin which does the above step for you also. If you are using
+CONFIG_SPL_FRAMEWORK, then u-boot.img will be built to include the device
+tree binary.
If CONFIG_OF_HOSTFILE is defined, then it will be read from a file on
startup. This is only useful for sandbox. Use the -d flag to U-Boot to
You cannot use more than one of these options at the same time.
+To use a device tree file that you have compiled yourself, pass
+EXT_DTB=<filename> to 'make', as in:
+
+ make EXT_DTB=boot/am335x-boneblack-pubkey.dtb
+
+Then U-Boot will copy that file to u-boot.dtb, put it in the .img file
+if used, and u-boot-dtb.bin.
+
If you wish to put the fdt at a different address in memory, you can
define the "fdtcontroladdr" environment variable. This is the hex
address of the fdt binary blob, and will override either of the options.
Be aware that this environment variable is checked prior to relocation,
when only the compiled-in environment is available. Therefore it is not
possible to define this variable in the saved SPI/NAND flash
-environment, for example (it will be ignored).
+environment, for example (it will be ignored). After relocation, this
+variable will be set to the address of the newly relocated fdt blob.
+It is read-only and cannot be changed. It can optionally be used to
+control the boot process of Linux with bootm/bootz commands.
To use this, put something like this in your board header file:
$ make DEVICE_TREE=<dts-file-name>
+Configuration Options
+---------------------
+
+A number of run-time configuration options are provided in the /config node
+of the control device tree. You can access these using fdtdec_get_config_int(),
+fdtdec_get_config_bool() and fdtdec_get_config_string().
+
+Available options are:
+
+silent-console
+ If present and non-zero, the console is silenced by default on boot.
+
+no-keyboard
+ Tells U-Boot not to expect an attached keyboard with a VGA console
+
+
Limitations
-----------
projects / J-u-boot.git / blobdiff