[Intel-gfx] [PATCH] drm/i915/gvt: disable GVT-g if host GuC submission is enabled

[Joonas Lahtinen]

On ma, 2017-05-08 at 10:30 +0000, Dong, Chuanxiao wrote:

<SNIP>

> > > > > +	if (i915.enable_guc_submission) {
> > > > > +		DRM_INFO("GPU guest virtualisation [GVT-g] disabled due to
> > > > > +enabled GuC submission [i915.enable_guc_submission module
> > > > > +parameter]\n");

<SNIP>

Something along the lines: "Graphics virtualization is not yet
supported with GuC" would be most informative to user.

> > > 
> > It needs to be verbose because it is a message to the user, it should tell them
> > what broke, what that will likely mean to them and if possible how to rectify.
> > Even then we know they won't read the entirety of the message but at least
> > it gives us a starting point for the inevitable bugs. We should always aim for
> > clarity and avoid too much jargon in DRM_INFO+.
> > 
> > In this case, you could argue that i915.enable_guc_submission is an unsafe
> > parameter set to off by default and so the combination of gvt + guc is pure
> > user error and they can keep both pieces.
> > 
> > Ideally we wouldn't use i915.enable_guc_submission at all, but gvt should be
> > disabled upon enabling guc -- since the combination is currently inoperable.
> > But again, this is just a user error and we can just -EIO the driver load...

I agree that currently when GuC submission is not enabled by default,
enabling it could result in -EIO on driver load if GVT is enabled
simultaneously.

When GuC gets enabled by default, it would be preferable for GVT team
to have support ready, or enable_gvt probably needs to become an
_unsafe param.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation