build-dtb-image: recurse vendor subdirs and prefer Debian standard DTB path with usrmerge fallback; build-rootfs: bypass zz-update-grub systemd guard in chroot

[bjordiscollaku]

Problem

Three independent failures surface when the CI pipeline switches from the
legacy build-kernel-deb.sh-generated package to the pkg-linux-qcom
Debian package (linux-image-<KVER>-qcom) built via debian/ metadata.

1 — build-dtb-image.sh: flat glob misses DTBs in vendor subdirectories

The FIT image build path collected DTBs using a flat glob:

cp -rap "${DTB_SRC}"/*.dtb* "${DTB_STAGE}/"

This assumes all DTB files reside directly in DTB_SRC. In practice,
DTBs are always installed one level deeper under a vendor subdirectory:

lib/firmware/<KVER>/device-tree/
  qcom/
    x1e80100-qcp.dtb
    sc8280xp-lenovo-thinkpad-x13s.dtb
    ...

When --kernel-deb is used, DTB_SRC resolves to the device-tree
directory (a symlink to the Debian-standard install path
usr/lib/linux-image-<KVER>/). The glob expands to nothing and the
build fails:

[INFO] Copying DTBs from /tmp/kernel-deb-ILIZ66/lib/firmware/7.0.0-rc5/device-tree ...
cp: cannot stat '/tmp/kernel-deb-ILIZ66/lib/firmware/7.0.0-rc5/device-tree/*.dtb*': No such file or directory
Error: Process completed with exit code 1.

2 — build-dtb-image.sh: device-tree directory not found in usrmerge packages

pkg-linux-qcom now installs the device-tree compat symlink under
usr/lib/firmware/<KVER>/device-tree (required to fix broken symlink
resolution on usrmerge systems where /lib → usr/lib). The previous
discovery glob only searched lib/firmware/*/device-tree:

dt_dirs=( "${DEB_DIR}/lib/firmware"/*/device-tree )

This expands to nothing for packages built with the updated debian/rules,
causing --kernel-deb mode to fail immediately after extraction.

3 — build-rootfs.sh: /boot/grub/grub.cfg never created in chroot

The pkg-linux-qcom postinst correctly follows the Debian standard of
delegating bootloader updates to /etc/kernel/postinst.d hooks. The
zz-update-grub hook (from grub-common) guards its update-grub call
with a systemd check:

if [ -d /run/systemd/system ]; then update-grub || true; fi

In a chroot, systemd is not running, so /run/systemd/system does not
exist and update-grub is silently skipped — /boot/grub/grub.cfg is
never created. The subsequent sed-based GRUB cleanup then fails:

sed: can't read /boot/grub/grub.cfg: No such file or directory
Error: Process completed with exit code 1.

The build-kernel-deb.sh-generated package called update-grub
unconditionally in its postinst, so it was unaffected.

---

Fix

1 — build-dtb-image.sh: recursive DTB collection

Replace the flat glob with find -L, which follows symlinks and recurses
into all vendor subdirectories, copying every *.dtb and *.dtbo file
flat into the mkimage staging directory (arch/arm64/boot/dts/qcom/),
as the ITS file expects:

while IFS= read -r dtb; do
    cp -p "${dtb}" "${DTB_STAGE}/"
done < <(find -L "${DTB_SRC}" \( -name '*.dtb' -o -name '*.dtbo' \) -type f)

find -L follows symlinks transparently, so this works correctly whether
device-tree is a real directory or a relative directory symlink (as
introduced in pkg-linux-qcom#11).

A post-copy count check and sorted DTB listing are also added so that an
empty or misconfigured DTB source is caught early with a clear diagnostic
rather than a cryptic mkimage FATAL ERROR:

[INFO] Staged 47 DTB file(s) to arch/arm64/boot/dts/qcom
[INFO] Staged DTBs:
        qcm6490-idp.dtb
        sc8280xp-lenovo-thinkpad-x13s.dtb
        ...

2 — build-dtb-image.sh: Debian-standard-first DTB discovery

Probe paths in order, falling back only if the preferred path is absent:

# 1. Debian standard install location (direct, no symlink — works on Debian and Ubuntu)
dt_dirs=( "${DEB_DIR}/usr/lib/linux-image-"*/ )
# 2. Ubuntu compat symlink (usrmerge layout)
if (( ${#dt_dirs[@]} == 0 )); then
    dt_dirs=( "${DEB_DIR}/usr/lib/firmware"/*/device-tree )
fi
# 3. Ubuntu compat symlink (legacy layout)
if (( ${#dt_dirs[@]} == 0 )); then
    dt_dirs=( "${DEB_DIR}/lib/firmware"/*/device-tree )
fi

Probing the Debian standard path first avoids any dependency on the Ubuntu
compat symlink and works correctly on pure Debian systems that never install
it. The fallback chain is fully backward compatible: legacy packages (built
by build-kernel-deb.sh) only populate lib/firmware/, so the script
falls through steps 1 and 2 and resolves via step 3 as before.

3 — build-rootfs.sh: explicit update-grub in chroot

Call update-grub explicitly in the chroot immediately after kernel
installation, bypassing the systemd guard. build-rootfs.sh owns the
chroot environment and is the right place to ensure grub.cfg is
generated — the kernel package postinst is intentionally unchanged:

yes "" | dpkg -i /linux-image-<KVER>-qcom.deb

# Run update-grub explicitly: the zz-update-grub hook skips it in a chroot
# because systemd is not running (/run/systemd/system absent).
update-grub

---

Changes

• kernel/scripts/build-dtb-image.sh: replace cp -rap *.dtb* flat glob
  with recursive find -L + cp loop in FIT image mode; add staged DTB
  count check and listing; probe usr/lib/linux-image-*/ first (Debian
  standard), then usr/lib/firmware/*/device-tree (usrmerge), then
  lib/firmware/*/device-tree (legacy) for full backward compatibility
• rootfs/scripts/build-rootfs.sh: call update-grub explicitly after
  kernel .deb installation to ensure /boot/grub/grub.cfg is generated
  in chroot environments where the zz-update-grub systemd guard skips it

---

Testing

# Fix 1+2 — DTB collection (pkg-linux-qcom package, Debian standard path)
./scripts/build-dtb-image.sh \
    --fit-image \
    --kernel-deb linux-image-7.0.0-rc5-qcom_1-1_arm64.deb \
    --metadata-commit 5d24fea316a512f85acf7a4528a118ce52223530 \
    --out dtb.bin
# Previously: cp: cannot stat '.../device-tree/*.dtb*': No such file or directory
#         or: No DTB directory found at '.../lib/firmware/*/device-tree'
# Now: DTBs collected from usr/lib/linux-image-.../ and staged correctly ✓
#      Falls back to lib/firmware/ for legacy packages ✓

# Fix 3 — GRUB config generation
./build-rootfs.sh \
    --product-conf qcom-product.conf \
    --seed seed.txt \
    --kernel-package linux-image-7.0.0-rc5-qcom_1-1_arm64.deb
# Previously: sed: can't read /boot/grub/grub.cfg: No such file or directory
# Now: update-grub runs in chroot, grub.cfg generated, sed cleanup succeeds ✓