OverlayFS on root filesystem not working in RPI5 due to wrong initramfs image update

System

RPI5 with up-to-date Bookworm lite installation.

Steps to Reproduce

Enable read-only file system and read-only boot partition in raspi-config > 4 Performance Options > P2 Overlay File System Enable/disable read-only file system
Reboot

Expected Results

Read-only mount for /boot/firmaware
Overlay mount for root, i.e. overlayroot on / type overlay (rw, ...

Actual Results

/boot/firmaware is read-only
ext4 mount for root: /dev/xxx on / type ext4 (rw, ...

Root Cause

Setting prementioned configs in raspi-config triggers installation of overlayroot package which runs imitramfs update (postinstall) but it seems that only rpi-v8 images are updated: (/boot/initrd.img-6.6.51+rpt-rpi-v8 and /boot/firmware/initramfs8). The same files are update by update-initramfs -u. However, some research revealed that RPI5 should run -rpi-2712 -kernel which indeed seems to be the case:

$ uname -a
Linux td1 6.6.51+rpt-rpi-2712 #1 SMP PREEMPT Debian 1:6.6.51-1+rpt3 (2024-10-08) aarch64 GNU/Linux

The problem can be resolved by updating correct image explicitly:

sudo update-initramfs -c -k $(uname -r)

Sytem Details

$ cat /etc/rpi-issue && cat /etc/os-release
Raspberry Pi reference 2024-11-19
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, 891df1e21ed2b6099a2e6a13e26c91dea44b34d4, stage2
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
NAME="Debian GNU/Linux"
VERSION_ID="12"
VERSION="12 (bookworm)"
VERSION_CODENAME=bookworm
...

$ apt policy initramfs-tools && apt policy overlayroot
initramfs-tools:
  Installed: 0.142+rpt1+deb12u1
  Candidate: 0.142+rpt1+deb12u1
  Version table:
 ...
overlayroot:
  Installed: 0.18.debian13+deb12u1
  Candidate: 0.18.debian13+deb12u1
  Version table:
 ...

raspberrypi / bookworm-feedback