Hi,
On 30-09-16 10:28, Hans de Goede wrote:
Hi,
<snip>
Xorg when running without a Xorg.conf searches for what it considers a "primary" gpu / video-card, basically it attempts to bring up the right card in setups where there are multiple cards and if it does not find one exits with an error.
The xserver has a 2 step process for finding the primary card:
- It searches for is a card which has a vga-bios mapped,
as we've already determined in the mentioned Red Hat bug that works for the classic qemu emulated video-cards, but not for qemu's virtio-vga.
- If that does not work Xorg will fallback to any video class device
on pci-bus 1.
This fallback actually has been broken in the Xorg xserver for quite a while now and only 2 days ago a patch from Laszlo was merged to fix this.
Only for things to break again due to this kernel patch.
Since the whole step 2) thingie is very much tied to x86 machines where pci-bus 0 used to be the main bus and pci-bus 1 the agp, which is sorta an obsolete assumption now a days and since relying on bus numbers / enumeration order is a bad idea in general I'm not entirely sure if this counts as a regression.
I've discussed the problem of the xserver exiting with an error when no primary device can be found with some people (ajax) at XDC last week since there are other use-cases where the pci-bus 1 fallback does not work.
As such I've been working on a xserver patch-set to make the xserver try harder (pick the first available device) when both steps described above fail to find one, which should make things work even with the newest (broken / regressed) kernels.
Given this mail thread, I guess I'm working after all today (I had planned a day off) and I'll try to wrap up this patch-set and reply to this mail with the server patches attached for Joachim and/or Laszlo to test.
Attached are 2 patches against the xserver which should fix this, please give them a try.
Regards,
Hans