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nixpkgs/pkgs/build-support/kernel/compress-firmware-xz.nix

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nixos/udev: compress all firmware if supported This should be a significant disk space saving for most NixOS installations. This method is a bit more complicated than doing it in the postInstall for the firmware derivations, but this way it's automatic, so each firmware package doesn't have to separately implement its compression. Currently, only xz compression is supported, but it's likely that future versions of Linux will additionally support zstd, so I've written the code in such a way that it would be very easy to implement zstd compression for those kernels when they arrive, falling back to xz for older (current) kernels. I chose the highest possible level of compression (xz -9) because even at this level, decompression time is negligible. Here's how long it took to decompress every firmware file my laptop uses: i915/kbl_dmc_ver1_04.bin 2ms regulatory.db 4ms regulatory.db.p7s 3ms iwlwifi-7265D-29.ucode 62ms 9d71-GOOGLE-EVEMAX-0-tplg.bin 22ms intel/dsp_fw_kbl.bin 65ms dsp_lib_dsm_core_spt_release.bin 6ms intel/ibt-hw-37.8.10-fw-22.50.19.14.f.bseq 7ms And since booting NixOS is a parallel process, it's unlikely (but difficult to measure) that the time to user interaction was held up at all by most of these. Fixes (partially?) #148197
2022-05-12 17:23:12 +02:00
{ runCommand }:
firmware:
runCommand "${firmware.name}-xz" {} ''
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) |
compressFirmwareXz: fix with empty lib/firmware Fixes: 8aa8e0ce7f1 ("nixos/udev: compress all firmware if supported")
2022-05-26 09:06:13 +02:00
(cd $out && xargs -0rtP "$NIX_BUILD_CORES" -n1 \
nixos/udev: compress all firmware if supported This should be a significant disk space saving for most NixOS installations. This method is a bit more complicated than doing it in the postInstall for the firmware derivations, but this way it's automatic, so each firmware package doesn't have to separately implement its compression. Currently, only xz compression is supported, but it's likely that future versions of Linux will additionally support zstd, so I've written the code in such a way that it would be very easy to implement zstd compression for those kernels when they arrive, falling back to xz for older (current) kernels. I chose the highest possible level of compression (xz -9) because even at this level, decompression time is negligible. Here's how long it took to decompress every firmware file my laptop uses: i915/kbl_dmc_ver1_04.bin 2ms regulatory.db 4ms regulatory.db.p7s 3ms iwlwifi-7265D-29.ucode 62ms 9d71-GOOGLE-EVEMAX-0-tplg.bin 22ms intel/dsp_fw_kbl.bin 65ms dsp_lib_dsm_core_spt_release.bin 6ms intel/ibt-hw-37.8.10-fw-22.50.19.14.f.bseq 7ms And since booting NixOS is a parallel process, it's unlikely (but difficult to measure) that the time to user interaction was held up at all by most of these. Fixes (partially?) #148197
2022-05-12 17:23:12 +02:00
sh -c 'xz -9c -T1 -C crc32 --lzma2=dict=2MiB "${firmware}/$1" > "$1.xz"' --)
(cd ${firmware} && find lib/firmware -type l) | while read link; do
target="$(readlink "${firmware}/$link")"
ln -vs -- "''${target/^${firmware}/$out}.xz" "$out/$link.xz"
done
''
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