U-Boot

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.

• pkgs/misc/uboot/default.nix

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 architecture
2. If you need to cross-compile

The target architecture is the architecture of the target board. For example, the LibreTechCC board uses the AArch64 architecture.

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 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.

To build with cross-compilation, you will 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

pkgsCross Cheat sheet

Architecture	Package Set
aarch64	aarch64-multiplatform
armv7l	armv7l-hf-multiplatform
armv6l	raspberryPi [sic]