Fixed: Black Screen after switching kernel

Hiya peoples,

Finally figured out what caused my black screen after updating

After installing a new kernel (via apt)  the '/boot/dtb' symlink is not updated, and fails to boot properly.

lrwxrwxrwx 1 root root       31 Oct  7 11:38 dtb -> dtb-6.11.2-edge-rockchip-rk3588
lrwxrwxrwx 1 root root       38 Oct  7 08:49 Image -> vmlinuz-6.11.2-current-rockchip-rk3588
lrwxrwxrwx 1 root root       38 Oct  7 08:49 uInitrd -> uInitrd-6.11.2-current-rockchip-rk3588

So I wrote a systemd service that:

1. Runs before shutdown/reboot

2. Changes into the /boot directory

3. Reads the version from the dtb symlink

4. Reads the version from the Image symlink

5. Compares the versions

6. And if they do NOT match, creates a new dtb symlink that matches the Image symlink version.

[Unit]
Description=match dtb symlink with kernel version
DefaultDependencies=no
Before=shutdown.target

[Service]
Type=oneshot
ExecStart=/bin/sh -c 'set -x;cd /boot;dtb=$(readlink dtb|sed 's,^dtb-,,');vmlinuz=$(readlink Image|sed 's,vmlinuz-,,');[ "$dtb" = "$vmlinuz" ] || ln -sf dtb-$vmlinuz dtb'
TimeoutStartSec=0

[Install]
WantedBy=shutdown.target

To use this:

1. sudo nano /etc/systemd/system/dtb-match-kernel.service and paste in the text above.

2. sudo systemd enable dtb-match-kernel.service

You can check the journal if it works with:

3. journalctl -u dtb-match-kernel.service

or the /boot directory

lrwxrwxrwx 1 root root       31 Oct  7 11:39 dtb -> dtb-6.11.2-current-rockchip-rk3588
lrwxrwxrwx 1 root root       38 Oct  7 08:49 Image -> vmlinuz-6.11.2-current-rockchip-rk3588
lrwxrwxrwx 1 root root       38 Oct  7 08:49 uInitrd -> uInitrd-6.11.2-current-rockchip-rk3588

Dantes

Edited October 8, 20242 yr by Dantes