Odroid HC4 does not boot on 6.18.0 kernel

[beorn63]

Board: Odroid HC4
Kernel package: linux-image-6.18.0-odroid-arm64 version 6.18.5-202601141840~trixie
OS: Debian GNU/Linux 13 (trixie)

Problem

After upgrading to kernel 6.18.0, the board no longer boots. Petitboot detects the Debian entry on the disk but the screen goes black (no HDMI signal) and the system never comes up — no SSH access, blue LED stays off.

Root cause

The DTB for the HC4 has been renamed in the 6.18.0 package:

• Old name (6.17.0 and earlier): meson64_odroidhc4.dtb
• New name (6.18.0): meson-sm1-odroid-hc4.dtb

However, flash-kernel still looks for meson64_odroidhc4.dtb in /usr/lib/linux-image-6.18.0-odroid-arm64/amlogic/ and cannot find it, producing the following warning during update-initramfs:

Couldn't find DTB meson64_odroidhc4.dtb in /usr/lib/linux-image-6.18.0-odroid-arm64 or /etc/flash-kernel/dtbs

As a result, boot.scr is generated with a missing or incorrect DTB reference, and the board fails to boot.

Workaround

Create a symlink in the kernel package directory to restore the expected filename:

sudo ln -s meson-sm1-odroid-hc4.dtb /usr/lib/linux-image-6.18.0-odroid-arm64/amlogic/meson64_odroidhc4.dtb
sudo update-initramfs -u -k 6.18.0-odroid-arm64

Note: even with this fix, kernel 6.18.0 still fails to boot on HC4 (no SSH, blue LED blinks but system never reaches userspace). The only working solution found was to revert to 6.17.0:

sudo flash-kernel --force 6.17.0-odroid-arm64
sudo apt-mark hold linux-image-6.18.0-odroid-arm64

Expected behavior

The DTB rename should either be accompanied by a corresponding update to the flash-kernel database, or backward-compatible symlinks should be included in the kernel package itself.