Dev/Embedded/FromScratch/UBoot - Revision history

Drizzt: /* Configure */

2025-07-27T17:12:34Z

Configure

← Older revision		Revision as of 19:12, 27 July 2025
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	There's no configuration stage for this part, though you'll need to know the "platform" name and the "target" name you want to build.		There's no configuration stage for this part, though you'll need to know the "platform" name and the "target" name you want to build.

	You can run "make help" to get the list of supported platform and the target names.		You can run "'''make help'''" to get the list of supported platform and the target names.

	You can refer to the documentation for your SoC (processor) under "docs/plat" directory.		You can refer to the documentation for your SoC (processor) under "docs/plat" directory.

Drizzt: /* Flash and Use */

2025-01-09T20:08:55Z

Flash and Use

← Older revision		Revision as of 22:08, 9 January 2025
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	There are many options, all depending on your hardware (the processor of course, but also the board you are using, which may have only some of the interfaces available, or specific "bootconfig" settings hardwired).<br />		There are many options, all depending on your hardware (the processor of course, but also the board you are using, which may have only some of the interfaces available, or specific "bootconfig" settings hardwired).<br />
	Here is a list of the common interfaces which may be available :		Here is a short list of the common interfaces which may be available :
	* Serial (one of the UARTs)		* Serial (one of the UARTs)
	* Onboard Flash (NAND, NOR or SPI Flash chips)		* Onboard Flash (NAND, NOR or SPI Flash chips)
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	Some options will require specific tools or services installed on your host, while others will require special configuration of a storage device (µSD card, USB key, ...).		Some options will require specific tools or services installed on your host, while others will require special configuration of a storage device (µSD card, USB key, ...).

	I'll provide some information on this Wiki for the boards I have, but if you want complete information about the possibilities you can have with a specific board the right place to look at is at the documentation. The board documentation may provide some information, though not necessarily all of it, so the best is to have a look at the processor documentation to know all the supported boot modes, and then at the board schematics (provided you have them) to know which ones are effectively available given the hardware configuration		I'll provide some information on this Wiki for the boards I have (on the board dedicated page), but if you want complete information about the possibilities you can have with a specific board the right place to look at is at the documentation. The board documentation may provide some information, though not necessarily all of it, so the best is to have a look at the processor documentation to know all the supported boot modes, and then at the board schematics (provided you have them) to know which ones are effectively available given the hardware configuration.

	== Next ==		== Next ==
	* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].		* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].
	* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading [[Dev/Embedded/FromScratch#Linux_Kernel\|the next step (Linux Kernel) from the "From Scratch" page]] if you came from there).		* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading [[Dev/Embedded/FromScratch#Linux_Kernel\|the next step (Linux Kernel) from the "From Scratch" page]] if you came from there).

Drizzt: /* Next */

2025-01-09T20:04:38Z

@@ Line 78: / Line 78: @@
 Set "platform" and "target" according to your needs as identified in the "Configure" section above
 == Next ==
 * Back to [[Dev/Embedded/FromScratch|"From Scratch" page]].
 * Move to [[Dev/Embedded/FromScratch/LinuxKernel|the linux kernel part]] (though you should go on reading [[Dev/Embedded/FromScratch#Linux_Kernel|the next step (Linux Kernel) from the "From Scratch" page]] if you came from there).

Drizzt: /* Next */

2024-12-30T01:35:59Z

← Older revision		Revision as of 03:35, 30 December 2024
Line 81:		Line 81:
	== Next ==		== Next ==
	* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].		* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].
	* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading [[Dev/Embedded/FromScratch#~~LinuxKernel~~\|the next step (Linux Kernel) from the "From Scratch" page]] if you came from there).		* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading [[Dev/Embedded/FromScratch#Linux_Kernel\|the next step (Linux Kernel) from the "From Scratch" page]] if you came from there).

Drizzt: /* Next */

2024-12-30T01:35:22Z

← Older revision		Revision as of 03:35, 30 December 2024
Line 81:		Line 81:
	== Next ==		== Next ==
	* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].		* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].
	* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading ~~the parts from the~~ [[Dev/Embedded/FromScratch\|"From Scratch" page]] if you came from there).		* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading [[Dev/Embedded/FromScratch#LinuxKernel\|the next step (Linux Kernel) from the "From Scratch" page]] if you came from there).

Drizzt: /* ARM trusted firmware (or Trusted Firmware-A) */

2024-12-30T01:18:25Z

ARM trusted firmware (or Trusted Firmware-A)

← Older revision		Revision as of 03:18, 30 December 2024
Line 78:		Line 78:

	Set "platform" and "target" according to your needs as identified in the "Configure" section above		Set "platform" and "target" according to your needs as identified in the "Configure" section above

			== Next ==
			* Back to [[Dev/Embedded/FromScratch\|"From Scratch" page]].
			* Move to [[Dev/Embedded/FromScratch/LinuxKernel\|the linux kernel part]] (though you should go on reading the parts from the [[Dev/Embedded/FromScratch\|"From Scratch" page]] if you came from there).

Drizzt: /* Compile */

2024-12-21T21:09:26Z

Compile

← Older revision		Revision as of 23:09, 21 December 2024
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	The result is at the root of the source tree. The image name to use depends on your target.		The result is at the root of the source tree. The image name to use depends on your target.

			How to use this image is highly dependent on your target board and SoC, so refer to the board specific information for this step !

	=== U-Boot environment ===		=== U-Boot environment ===

Drizzt: Created page with "== U-Boot == === Introduction === For most of the boards I have I'm using U-Boot as bootloader (some may be supported by other bootloaders, but I usually stick to the bootloader proposed by the board manufacturer). "Das U-Boot" (https://www.denx.de/project/u-boot/) is one of the most used bootloader for embedded systems running Linux. It supports a wide range of hardware and many boot mechanisms (serial, ethernet, flash, USB, SD card, emmc, ...) to load the necessary im..."

2024-12-09T14:13:16Z

Created page with "== U-Boot == === Introduction === For most of the boards I have I'm using U-Boot as bootloader (some may be supported by other bootloaders, but I usually stick to the bootloader proposed by the board manufacturer). "Das U-Boot" (https://www.denx.de/project/u-boot/) is one of the most used bootloader for embedded systems running Linux. It supports a wide range of hardware and many boot mechanisms (serial, ethernet, flash, USB, SD card, emmc, ...) to load the necessary im..."

New page

== U-Boot ==
=== Introduction ===
For most of the boards I have I'm using U-Boot as bootloader (some may be supported by other bootloaders, but I usually stick to the bootloader proposed by the board manufacturer).

"Das U-Boot" (https://www.denx.de/project/u-boot/) is one of the most used bootloader for embedded systems running Linux.
It supports a wide range of hardware and many boot mechanisms (serial, ethernet, flash, USB, SD card, emmc, ...) to load the necessary images required to boot the system. 
Details will be found in u-boot documentation.

=== Get the sources ===
Most of the time the official u-boot sources (from denx.de) are fine :
git clone git://git.denx.de/u-boot.git

If your board is not supported by the official u-boot sources, refer to your board documentation to get the bootloader sources.
Depending on your hardware, you may need to use a specific release of u-boot. Use git checkout to get the right one.

=== Configure ===
If your hardware is supported by u-boot you should find a "<board_name>_defconfig" file in the "configs" directory at the root of the git tree. 
If you do not know which one to use, you can refer to your board's documentation, or to u-boot documentation under "doc/board". 
Then the configuration is made in two steps :
board_name=
compiler_prefix=
make CROSS_COMPILE=${compiler_prefix} ${board_name}_defconfig
make CROSS_COMPILE=${compiler_prefix} menuconfig

If the default configuration fits your needs the second step (menuconfig) is not required.

=== Compile ===
Once you're done with the configuration step, the compilation is made by running make from the source tree root with the "CROSS_COMPILE" variable set.

Note that for boards which require an ARM trusted firmware image it may be required to export a variable with it's path first :
platform=
target=
path_to_atf=
export BL31=${path_to_atf}/build/${platform}/debug/${target}.bin
Refer to the "ARM trusted firmware" section bellow to build this firmware image first.

And compile :
compiler_prefix=
make CROSS_COMPILE=${compiler_prefix}

The result is at the root of the source tree. The image name to use depends on your target.

=== U-Boot environment ===
Part of u-boot configuration includes a default environment, which holds various variables used to help loading and starting the Linux kernel. 
Some of these variables have predefined meaning and other are user defined to help configure u-boot behavior. 
Depending on your hardware, the default variables can be overridden from the content of a saved environment from a flash location, or from the content of a script. This helps save board specific boot configuration and select boot mechanism used to load and start the required binaries. 
Whatever the mechanism used to get them, it usually boils down to loading the Linux kernel image, an optional initramfs or initrd image (which may also be included in the Linux kernel image or not required at all), and a device tree blob (dtb) if it is not included within the Linux kernel image. 
The bootloader also has to provide a command line to the Linux kernel, unless the Linux kernel image has a default command line compiled in. This is done by setting the "bootargs" environment variable. 
The effective boot is done then by running one of the boot commands supported by the u-boot image. 
Refer to each board description for a list of board specific configurations and for example boot scripts when supported.

== ARM trusted firmware (or Trusted Firmware-A) ==
If you are building U-Boot for an arm64/aarch64 device, you need to include the "ARM trusted firmware" (ATF) or "Trusted Firmware-A" (TF-A).

=== Get the sources ===
You can get this either from the trustedfirmware.org git repository :
git clone https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git
These sources are also available from the arm-trusted-firmware git repository on github : https://github.com/ARM-software/arm-trusted-firmware.git 
Note that both repository seems to have the same code, only some of the tags appear to be different.

=== Configure ===
There's no configuration stage for this part, though you'll need to know the "platform" name and the "target" name you want to build.

You can run "make help" to get the list of supported platform and the target names.

You can refer to the documentation for your SoC (processor) under "docs/plat" directory.

I'll indicate the right plaform and target on the pages dedicated to each board when I get my hands on them :)

=== Compile ===
To build this firmware part get to the root of the git tree and run:
platform=
target=
compiler_prefix=
make CROSS_COMPILE=${compiler_prefix} PLAT=${platform} DEBUG=1 ${target}

Set "platform" and "target" according to your needs as identified in the "Configure" section above