U-Boot: Difference between revisions

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You need to know two things:
You need to know two things:


# The target architecture
# The target ISA (''Instruction Set Architecture'')
# If you need to cross-compile
# If you need to cross-compile


The target architecture is the ''architecture'' of the target board. For example, the <code>LibreTechCC</code> board uses the <code>AArch64</code> ''architecture''.
The target ISA is the ISA of the ''target board''. This would be defined by the CPU used on the board.


You will need to cross-compile if you are not building on the same ''architecture'' as the target board. For example, if you are building on a standard <code>x86_64</code> laptop, you would need to cross-compile.
You will need to cross-compile if you are not building on the same ''architecture'' as the target board. For example, if you are building for an <code>AArch64</code> ''target board'' on a standard <code>x86_64</code> laptop, you would need to cross-compile.


With those facts known, you can build the appropriate attribute from a Nixpkgs checkout.
With those facts known, you can build the appropriate attribute from a Nixpkgs checkout.
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$ nix-build -A [pkgsCross.$cross_name.]$packageName
$ nix-build -A [pkgsCross.$cross_name.]$packageName
$ # Where the part in [brackets] is needed for cross-compilation.
$ # Where the part in [brackets] is needed for cross-compilation.
</syntaxhighlight>To build with cross-compilation, you will need to prefix with the correct cross-compilation package set:<syntaxhighlight lang="shell-session">
$ # Example running on x86_64.
$ uname -m
x86_64
$ nix-build -A pkgsCross.aarch64-multiplatform.ubootLibreTechCC
</syntaxhighlight>If, instead, you are building natively (same architecture) you can refer to the package attribute name directly:<syntaxhighlight lang="shell-session">
$ # Example output for an AArch64 system.
$ uname -m
aarch64
$ nix-build -A ubootLibreTechCC
</syntaxhighlight>
</syntaxhighlight>
=== <code>pkgsCross</code> Cheat sheet ===
{| class="wikitable"
{| class="wikitable"
|+
<code>pkgsCross</code> attribute name cheat sheet
!Architecture
!Architecture
!Package Set
!Package Set
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|<code>raspberryPi</code> ''[sic]''
|<code>raspberryPi</code> ''[sic]''
|}
|}
==== Example build ====
The following examples use the U-Boot package for a ''LibreTech CC ‘LePotato’'', which uses an ''S905X'' SoC. This SoC uses an <code>AArch64</code> ISA.
To build the package with cross-compilation, you need to prefix with the correct cross-compilation package set:<syntaxhighlight lang="shell-session">
$ # Example running on x86_64.
$ uname -m
x86_64
$ nix-build -A pkgsCross.aarch64-multiplatform.ubootLibreTechCC
</syntaxhighlight>If, instead, you are building natively (same architecture) you can refer to the package attribute name directly:<syntaxhighlight lang="shell-session">
$ # Example output for an AArch64 system.
$ uname -m
aarch64
$ nix-build -A ubootLibreTechCC
</syntaxhighlight>


=== Using U-Boot ===
=== Using U-Boot ===
You will need to consult either the [https://docs.u-boot.org/ Official U-Boot documentation], or a board-specific page to find out how to use the produced output.
You will need to consult either the [https://docs.u-boot.org/ Official U-Boot documentation], or a board-specific page to find out how to use the produced output.


The large variety of ecosystems supported by U-Boot makes it impossible to document succintly.
The large variety of ecosystems supported by U-Boot makes it impossible to document succinctly.


==== SBC and related projects in NixOS ====
==== SBC and related projects in NixOS ====
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== Other U-Boot distributions ==
== Other U-Boot distributions ==
There exists other prebuilt U-Boot distributions. As long as they follow the mainline U-Boot semantics, and are close enough in age to the current releases, they should work to boot NixOS.
There exists other pre-built U-Boot distributions. As long as they follow the mainline U-Boot semantics, and are close enough in age to the current releases, they should work to boot NixOS.


=== Tow-Boot ===
=== Tow-Boot ===

Revision as of 04:03, 7 April 2024

U-Boot is a common platform firmware implementation for embedded and embedded-like devices.

It may also be used as a bootloader, but with modern U-Boot, UEFI boot is generally possible too.

U-Boot in Nixpkgs

Mainline U-Boot is packaged in Nixpkgs.

Vendor forks of U-Boot are generally not packaged in Nixpkgs, and generally unwelcome.

U-Boot may be patched for compatibility reasons mainly, and work should be taken to send them to mainline U-Boot.

Building a packaged U-Boot

You need to know two things:

  1. The target ISA (Instruction Set Architecture)
  2. If you need to cross-compile

The target ISA is the ISA of the target board. This would be defined by the CPU used on the board.

You will need to cross-compile if you are not building on the same architecture as the target board. For example, if you are building for an AArch64 target board on a standard x86_64 laptop, you would need to cross-compile.

With those facts known, you can build the appropriate attribute from a Nixpkgs checkout.

The general format is:

$ nix-build -A [pkgsCross.$cross_name.]$packageName
$ # Where the part in [brackets] is needed for cross-compilation.
pkgsCross attribute name cheat sheet
Architecture Package Set
aarch64 aarch64-multiplatform
armv7l armv7l-hf-multiplatform
armv6l raspberryPi [sic]

Example build

The following examples use the U-Boot package for a LibreTech CC ‘LePotato’, which uses an S905X SoC. This SoC uses an AArch64 ISA.

To build the package with cross-compilation, you need to prefix with the correct cross-compilation package set:

$ # Example running on x86_64.
$ uname -m 
x86_64
$ nix-build -A pkgsCross.aarch64-multiplatform.ubootLibreTechCC

If, instead, you are building natively (same architecture) you can refer to the package attribute name directly:

$ # Example output for an AArch64 system.
$ uname -m 
aarch64
$ nix-build -A ubootLibreTechCC

Using U-Boot

You will need to consult either the Official U-Boot documentation, or a board-specific page to find out how to use the produced output.

The large variety of ecosystems supported by U-Boot makes it impossible to document succinctly.

SBC and related projects in NixOS

Vendor U-Boot

Vendor U-Boot may or may not work to boot and use NixOS.

The answer is actually really complicated, and depends not only about U-Boot, but the intended Linux kernel to be booted, and the boot method in use.

The buildUBoot implementation in Nixpkgs may or may not work to build a vendor U-Boot, and this usage is unsupported.

A few vendors ship good pre-built modern U-Boot implementations. Booting NixOS with those should work. If it does not, things may need to be fixed on any of the end. But also, this depends on the kernel, and boot method in use.

Other U-Boot distributions

There exists other pre-built U-Boot distributions. As long as they follow the mainline U-Boot semantics, and are close enough in age to the current releases, they should work to boot NixOS.

Tow-Boot

Aside: Tow-Boot is not a NixOS project.
Though it is built with Nix expressions, and made by authors involved with the NixOS project.

Stock NixOS should be assumed to work with Tow-Boot, always depending on the boot method and kernel in use.

Tow-Boot is currently used as a reference as the only distro-agnostic U-Boot build, for support purposes.

See also

Retrieved from "https://wiki.nixos.org/w/index.php?title=U-Boot&oldid=11823"