Bug#1005783: xorg-server: "no screens found" when run under: kvm -vga virtio

[Philip Hands <phil@hands.com>]

Source: xorg-server
Version: 2:21.1.3-2
Severity: normal

Dear Maintainer,

[I'm reporting this against the source because I'm not sure which binary is at
fault, but this presuambly related to the bits of xorg that gets put into a udeb
and it has been seen while testing on amd64.]

Daily Debian-Installer images made after Feb 9 are failing to start X, as seen here:

  https://openqa.debian.net/tests/42033#step/_boot_to_debianinstaller/4

which conicides with 2:21.1.3-2 hitting unstable, which suggests that is what is
responsible for the change.

Here is that same test, using the version of D-I built at 2022-02-09 22:16:

  https://openqa.debian.net/tests/41989#step/_boot_to_debianinstaller/3

which, as you can see, gets to run X.

If I set things such that it uses `-vga std` instead of `-vga virtio`, and do a
BIOS boot, it is again able to start X:

  https://openqa.debian.net/tests/42370#step/_boot_to_debianinstaller/3

However, a UEFI boot still fails (with `-vga std`):

  https://openqa.debian.net/tests/42416#step/_boot_to_debianinstaller/4

BTW One can reproduce this behaviour by running kvm thus:

  kvm -cdrom debian-testing-amd64-netinst.iso -m 1G
  (which works, because it's defaulting to: -vga std )

and:

  kvm -cdrom debian-testing-amd64-netinst.iso -m 1G -vga virtio
  (which fails for recent versions, and works for versions produced up until Feb 9)

If you need an earlier copy of a daily image, for comparision purposes, I have
copies at present, and can put them somewhere you can get them.

Cheers, Phil.