Comment # 5 on bug 993091 from Wolfgang Bauer

As the 32bit guest tools are included in Tumbleweed again, I tried a fresh
installation (I can only run 32bit guests in VirtualBox here) and experienced
the same.
Adding the iomem=relaxed kernel parameter fixed it.

The problem is that the vboxvideo kernel module fails to load, so the UMS video
driver is used which only works with iomem=relaxed (IIRC there was a thread
about this already a while ago).

The kernel module fails to load because of this:
vboxvideo: no symbol version for VBoxGuest_RTLogBackDoorPrintf
vboxvideo: Unknown symbox VBoxGuest_RTLogBackdoorPrintf (err -22)
(and a few more similar messages in dmesg). See also bug#983927.

I have a fix for this as well though which I will submit tomorrow.