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nixos-hardware/raspberry-pi/4/apply-overlays-dtmerge.nix
Ivan Petkov 320866b985
raspberry-pi/4/dtmerge: fix application of overlays
Previously whenever an overlay was found to be incompatible with a base
device tree blob, the entire base dtb would be skipped in favor of
processing the next one. This had the unfortunate effect where overlays
would not fully be applied if any incompatibility was found. For
example, this is an issue with build device trees specific for one
flavor of raspberry pi if the overlay was not compatible _everywhere_.

The solution is to forego the `continue` keyword if an overlay is in
compatible and instead use a compound conditional statement to skip
incompatible overlays but continue trying to apply it to any remaining
dtbs.
2023-01-16 19:57:10 -08:00

48 lines
1.8 KiB
Nix

# modification of nixpkgs deviceTree.applyOverlays to resolve https://github.com/NixOS/nixpkgs/issues/125354
# derived from https://github.com/NixOS/nixpkgs/blob/916ca8f2b0c208def051f8ea9760c534a40309db/pkgs/os-specific/linux/device-tree/default.nix
{ lib, stdenvNoCC, dtc, libraspberrypi }:
with lib; (base: overlays': stdenvNoCC.mkDerivation {
name = "device-tree-overlays";
nativeBuildInputs = [ dtc libraspberrypi ];
buildCommand = let
overlays = toList overlays';
in ''
mkdir -p $out
cd "${base}"
find . -type f -name '*.dtb' -print0 \
| xargs -0 cp -v --no-preserve=mode --target-directory "$out" --parents
for dtb in $(find "$out" -type f -name '*.dtb'); do
dtbCompat=$(fdtget -t s "$dtb" / compatible 2>/dev/null || true)
# skip files without `compatible` string
test -z "$dtbCompat" && continue
${flip (concatMapStringsSep "\n") overlays (o: ''
overlayCompat="$(fdtget -t s "${o.dtboFile}" / compatible)"
# skip incompatible and non-matching overlays
if [[ ! "$dtbCompat" =~ "$overlayCompat" ]]; then
echo "Skipping overlay ${o.name}: incompatible with $(basename "$dtb")"
elif ${if ((o.filter or null) == null) then "false" else ''
[[ "''${dtb//${o.filter}/}" == "$dtb" ]]
''}
then
echo "Skipping overlay ${o.name}: filter does not match $(basename "$dtb")"
else
echo -n "Applying overlay ${o.name} to $(basename "$dtb")... "
mv "$dtb"{,.in}
# dtmerge requires a .dtbo ext for dtbo files, otherwise it adds it to the given file implicitly
dtboWithExt="$TMPDIR/$(basename "${o.dtboFile}").dtbo"
cp -r ${o.dtboFile} "$dtboWithExt"
dtmerge "$dtb.in" "$dtb" "$dtboWithExt"
echo "ok"
rm "$dtb.in" "$dtboWithExt"
fi
'')}
done'';
})