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

[Alexander Betaev]

Hi Alex,

Thank you, that helped immediately!

--
Best regards,
Alexander Betaev


On Sat, Sep 19, 2015 at 4:08 PM, Alex Williamson
<alex.l.williamson at gmail.com> wrote:
> On Fri, Sep 18, 2015 at 10:36 AM, Alexander Betaev <betaev at gmail.com> wrote:
>>
>> 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.
>
>
> If you're using OVMF for the assigned GPU VMs, then add the option
> disable_vga=1 to the vfio-pci module and make sure the other GPUs are bound
> to vfio-pci before Xorg starts on the host.  This disables VGA region access
> through vfio and opts-out the bound devices from VGA arbitration, leaving
> only one participant on the host.  If you're using x-vga=on, there's really
> nothing that can be done without some code changes in Xorg.