[vfio-users] IGD (HD4600) hardware acceleration is disabled in some cases on host

[Alexander Betaev]

Hello,

I noticed very strange behavior of HD4600 as host GPU.
I have the following configuration: two cards (ATI&nVIdia) are passed
through to two guest VMs and IGD is used as host GPU. But in several
cases X server wont start with hardware acceleration saying:
[    21.629] (II) Found 2 VGA devices: arbiter wrapping enabled
[    21.635] (II) SELinux: Disabled on system
[    21.636] (II) AIGLX: Screen 0 is not DRI2 capable
[    21.636] (EE) AIGLX: reverting to software rendering
[    21.780] (II) AIGLX: Loaded and initialized swrast
[    21.780] (II) GLX: Initialized DRISWRAST GL provider for screen 0

The scenario:
1. System boots up and start GDM
2. The *first user* logs in and has software rendering
3. *Second user* switches session (without terminating X with software
rendering) and new X server has hardware rendering
4. When *second user* logs out, GDM shows up in X with software
rendering, but if a user logs in as *first user* and then switches
user then GDM shows up in X with HW accelerated rendering. So the next
session will be started with HW rendering

The workaround is obvious, but not convenient if host is used by
several users. Starting gnome-shell in Wayland also solves the issue,
but Wayland is very unstable in distribution I use.

System is Debian 8.0 (Jessie/Stable) .The versions of packages:
* xserver-xorg-video-intel 2:2.99.917-2~bpo8+1
* linux-image-amd64 4.1+67~bpo8+1
* gdm3 3.14.1-7
* xserver-xorg-core 2:1.16.4-1

Please advise.


Thanks.

--
Best regards,
Alexander Betaev