nixpkgs/pkgs/build-support/kernel/compress-firmware.nix
Maximilian Bosch b6ef9ffdfd
nixos/udev: compress firmware with zstd if possible
Closes #267442

    $ nix path-info -Sh /nix/store/qj1dm7wfw5m3mxf1gn3fdm0az9y1h5ny-linux-firmware-20240312-xz
    /nix/store/qj1dm7wfw5m3mxf1gn3fdm0az9y1h5ny-linux-firmware-20240312-xz	440.3M
    $ nix path-info -Sh /nix/store/c3szcjxb3g990dbiz7llwmkaf0bi98j2-linux-firmware-20240312-zstd
    /nix/store/c3szcjxb3g990dbiz7llwmkaf0bi98j2-linux-firmware-20240312-zstd	460.6M

This is an increase of 4.4%, but OTOH zstd has a significantly higher
decompression speed[1].

[1] https://gregoryszorc.com/blog/2017/03/07/better-compression-with-zstandard/
2024-04-19 16:46:25 +02:00

43 lines
1.4 KiB
Nix

{ runCommand, lib, type ? "zstd", zstd }:
firmware:
let
compressor = {
xz = {
ext = "xz";
nativeBuildInputs = [ ];
cmd = file: target: ''xz -9c -T1 -C crc32 --lzma2=dict=2MiB "${file}" > "${target}"'';
};
zstd = {
ext = "zst";
nativeBuildInputs = [ zstd ];
cmd = file: target: ''zstd -T1 -19 --long --check -f "${file}" -o "${target}"'';
};
}.${type} or (throw "Unsupported compressor type for firmware.");
args = {
allowedRequisites = [];
inherit (compressor) nativeBuildInputs;
} // lib.optionalAttrs (firmware ? meta) { inherit (firmware) meta; };
in
runCommand "${firmware.name}-${type}" args ''
mkdir -p $out/lib
(cd ${firmware} && find lib/firmware -type d -print0) |
(cd $out && xargs -0 mkdir -v --)
(cd ${firmware} && find lib/firmware -type f -print0) |
(cd $out && xargs -0rtP "$NIX_BUILD_CORES" -n1 \
sh -c '${compressor.cmd "${firmware}/$1" "$1.${compressor.ext}"}' --)
(cd ${firmware} && find lib/firmware -type l) | while read link; do
target="$(readlink "${firmware}/$link")"
if [ -f "${firmware}/$link" ]; then
ln -vs -- "''${target/^${firmware}/$out}.${compressor.ext}" "$out/$link.${compressor.ext}"
else
ln -vs -- "''${target/^${firmware}/$out}" "$out/$link"
fi
done
echo "Checking for broken symlinks:"
find -L $out -type l -print -execdir false -- '{}' '+'
''