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nixpkgs/pkgs/build-support/kernel/modules-closure.sh
Alyssa Ross 8aa8e0ce7f
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
2022-05-13 14:36:34 +00:00

102 lines
3.7 KiB
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source $stdenv/setup
# When no modules are built, the $out/lib/modules directory will not
# exist. Because the rest of the script assumes it does exist, we
# handle this special case first.
if ! test -d "$kernel/lib/modules"; then
if test -z "$rootModules" || test -n "$allowMissing"; then
mkdir -p "$out"
exit 0
else
echo "Required modules: $rootModules"
echo "Can not derive a closure of kernel modules because no modules were provided."
exit 1
fi
fi
version=$(cd $kernel/lib/modules && ls -d *)
echo "kernel version is $version"
# Determine the dependencies of each root module.
mkdir -p $out/lib/modules/"$version"
touch closure
for module in $rootModules; do
echo "root module: $module"
modprobe --config no-config -d $kernel --set-version "$version" --show-depends "$module" \
| while read cmd module args; do
case "$cmd" in
builtin)
touch found
echo "$module" >>closure
echo " builtin dependency: $module";;
insmod)
touch found
if ! test -e "$module"; then
echo " dependency not found: $module"
exit 1
fi
target=$(echo "$module" | sed "s^$NIX_STORE.*/lib/modules/^$out/lib/modules/^")
if test -e "$target"; then
echo " dependency already copied: $module"
continue
fi
echo "$module" >>closure
echo " copying dependency: $module"
mkdir -p $(dirname $target)
cp "$module" "$target"
# If the kernel is compiled with coverage instrumentation, it
# contains the paths of the *.gcda coverage data output files
# (which it doesn't actually use...). Get rid of them to prevent
# the whole kernel from being included in the initrd.
nuke-refs "$target"
echo "$target" >> $out/insmod-list;;
*)
echo " unexpected modprobe output: $cmd $module"
exit 1;;
esac
done || test -n "$allowMissing"
if ! test -e found; then
echo " not found"
if test -z "$allowMissing"; then
exit 1
fi
else
rm found
fi
done
mkdir -p $out/lib/firmware
for module in $(cat closure); do
# for builtin modules, modinfo will reply with a wrong output looking like:
# $ modinfo -F firmware unix
# name: unix
#
# There is a pending attempt to fix this:
# https://github.com/NixOS/nixpkgs/pull/96153
# https://lore.kernel.org/linux-modules/20200823215433.j5gc5rnsmahpf43v@blumerang/T/#u
#
# For now, the workaround is just to filter out the extraneous lines out
# of its output.
for i in $(modinfo -b $kernel --set-version "$version" -F firmware $module | grep -v '^name:'); do
mkdir -p "$out/lib/firmware/$(dirname "$i")"
echo "firmware for $module: $i"
for name in "$i" "$i.xz" ""; do
[ -z "$name" ] && echo "WARNING: missing firmware $i for module $module"
if cp "$firmware/lib/firmware/$name" "$out/lib/firmware/$name" 2>/dev/null; then
break
fi
done
done
done
# copy module ordering hints for depmod
cp $kernel/lib/modules/"$version"/modules.order $out/lib/modules/"$version"/.
cp $kernel/lib/modules/"$version"/modules.builtin $out/lib/modules/"$version"/.
depmod -b $out -a $version
# remove original hints from final derivation
rm $out/lib/modules/"$version"/modules.order
rm $out/lib/modules/"$version"/modules.builtin