Re: [Qemu-devel] [PATCH v4 0/7] vfio: add display support

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 20 Feb 2018 11:28:14 +0100
Gerd Hoffmann <kraxel@redhat.com> wrote:

> On Mon, Feb 19, 2018 at 03:16:49PM -0700, Alex Williamson wrote:
> > On Mon, 19 Feb 2018 12:14:51 +0100
> > Gerd Hoffmann <kraxel@redhat.com> wrote:
> >   
> > > This series adds support for a vgpu display to the qemu vfio code.
> > > For now only regions are supported, dmabufs will follow later.
> > > 
> > > This version adds a patch to allow devices disable hotplugging, which
> > > will be used by vfio display support.  Also fixed issues Alex found in
> > > review.  
> > 
> > Looks ok to me, if this is to go through my tree I'll need a qdev ack
> > for 4/7.  If you want to go a different route, for 5-7:
> > 
> > Acked-by: Alex Williamson <alex.williamson@redhat.com>
> > 
> > I'm still a bit confused though, what's preventing us from adding
> > dmabuf support now?  It's strange to provide the implementation for the
> > proprietary, unavailable vendor driver implementation first.  Is GVT-g
> > broken, lagging?  Thanks,  
> 
> A bit more complicated because it depends on user interface changes ...
> 
> Sneak preview at https://www.kraxel.org/cgit/qemu/log/?h=work/intel-vgpu
> Note: branch is a moving target ;)
> 
> State:
>   vfio:  Working, needs some cleanups though (drop debug logging, ...).
>   gtk:   Working, needs some minor cleanups too.
>   spice: Partly working (no mouse ptr yet).
>   sdl:   Not working.  Need to figure how I get a egl context (instead
>          of glx).  Possibly requires SDL 2.2.  Tina looked at this a
>          while back, need to look at some old mails ...
> 
> Current plan:
>   (1) fix/complete spice support.
>   (2) cleanup patches, send them out.
>   (3) look at the SDL issues.

Hi Gerd,

It's a little bit concerning that the only way we can test the
region-based display support is with proprietary drivers that nobody
but NVIDIA has at this point.  Have you considered adding region-based
display support to the mdev sample tty driver?  I know it sounds
ridiculous for a serial device to have a display, but the vfio display
region support isn't really tied to the functionality of the base mdev
device.  We could have it simply display a static test pattern, just so
we can test the end to end code path without a dependency on a closed
vendor driver.  Thanks,

Alex