Bug#908005: nvidia-driver: When initializing vulkan, driver opens default XDisplay

[Luca Boccassi]

On Fri, 2018-09-07 at 19:13 +0200, Felix Dörre wrote:
> On 9/7/18 12:27 PM, Luca Boccassi wrote:
> > Control: reassign -1 bumblebee
> > Control: forcemerge 892646 -1
> > 
> > On Wed, 2018-09-05 at 06:52 +0200, Felix Dörre wrote:
> > > Package: nvidia-driver
> > > Version: 390.77-1
> > > Severity: important
> > > 
> > > Dear Maintainer,
> > > 
> > > I have an Nvidia-Optimus setup and use bumblebee to activate the
> > > Nvidia GPU on demand.
> > > 
> > > When I use libvulkan.so.1 to run a Vulkan application the ICD
> > > from
> > > Nvidia (installed in /usr/share/vulkan/icd.d/nvidia_icd.json,
> > > /usr/lib/x86_64-linux-gnu/nvidia/libGL.so.1) opens a connection
> > > to
> > > the
> > > default X Display (as specified by the DISPLAY environment
> > > variable).
> > > When using bumblebee to activate the Nvidia GPU, the driver must
> > > connect to Display :8, where bumblebee runs the secondary
> > > X Server. However I want to run my application with the DISPLAY
> > > environment variable set to :0 (as I want it displayed on :0).
> > > 
> > > I generally would expect the Vulkan-Nvidia driver not to require
> > > an
> > > X-connection when doing headless rendering and for 'normal'
> > > rendering
> > > use the X-connection/display that is indicated by the surface-
> > > creation functions, and not choose one by itself on startup.
> > > If that is hard to achieve, I would at least expext the Nvidia-
> > > Driver
> > > to have some override environment variable (like e.g. NV_DISPLAY)
> > > that, when set, is passed by the Nvidia-Driver to XOpenDisplay,
> > > that
> > > "normal" applications would ignore.
> > 
> > Hi, Vulkan is not supported on Optimus, see #892646.
> > 
> 
> :-) Yes, that's exactly what I am currently trying to implement when
> I 
> encountered this problem. The misbehavior I am describing is a
> problem 
> in the nvidia driver that obstructs me from implementing a primus-
> like 
> solution for vulkan. For this I only use bumblebee to activate the
> GPU 
> and don't use/need primus for the GL-bridge.
> 
> Additionally I believe that also non-Optimus users can encounter
> this 
> problem in non-standard usage scenarios, when the environment
> variable 
> DISPLAY is wrong and the application uses another way to determine
> the 
> correct display to call XOpenDisplay upon. The driver will then fail
> to 
> load, however it should not depend on $DISPLAY at all.

That's why I wrote Optimus, as far as I'm aware I don't believe there
is any support from Nvidia in the proprietary drivers to do that at the
moment, you'll need to report it to Nvidia, but I wouldn't hold my
breath...

-- 
Kind regards,
Luca Boccassi
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