RTL8153 USB NIC stays down during LINBO boot with current kernel

[garblixa]

Since updating LINBO to the current kernel (7.5.1), USB network adapters with Realtek RTL8153 (0bda:8153) no longer work during LINBO boot.

With the legacy kernel the adapter works, but legacy is not an option for us because newer laptops then have problems with their storage controllers.

r8152 is present and loaded, eth0 exists after LINBO has booted but is down after boot and LINBO shows "OFFLINE".

What I found so far:

After LINBO has booted, this is enough to get the network working:

ip link set eth0 up

After that:

ethtool eth0

shows:

Link detected: yes

and running udhcpc immediately gets a valid IP address.

The problem looks like the network interface is not yet available/ready when LINBO initializes networking.

I tested this by adding a short wait before LINBO's network initialization implementing /var/lib/linuxmuster/hooks/update-linbofs.pre.d/wait-usb-nic hook. With this hook the machine boots into LINBO with working network. If I remove the hook and rebuild linbofs, the problem is reproducible again.

So it looks like there is a timing issue with USB network adapters which appear slightly later with the current kernel.

The workaround is basically to wait for eth0 before running the normal LINBO network initialization, for example:

/var/lib/linuxmuster/hooks/update-linbofs.pre.d/wait-usb-nic

i=0
while [ ! -e /sys/class/net/eth0 ] && [ "$i" -lt 10 ]; do
    sleep 1
    i=$((i+1))
done

update-linbofs