RE: [PATCH v10] vfio: ABI for mdev display dma-buf operation

[Zhang, Tina]

> -----Original Message-----
> From: Gerd Hoffmann [mailto:kraxel@xxxxxxxxxx]
> Sent: Monday, July 17, 2017 7:03 PM
> To: Kirti Wankhede <kwankhede@xxxxxxxxxx>; Zhang, Tina
> <tina.zhang@xxxxxxxxx>; Tian, Kevin <kevin.tian@xxxxxxxxx>; linux-
> kernel@xxxxxxxxxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx;
> alex.williamson@xxxxxxxxxx; zhenyuw@xxxxxxxxxxxxxxx; chris@chris-
> wilson.co.uk; Lv, Zhiyuan <zhiyuan.lv@xxxxxxxxx>; intel-gvt-
> dev@xxxxxxxxxxxxxxxxxxxxx; Wang, Zhi A <zhi.a.wang@xxxxxxxxx>
> Subject: Re: [PATCH v10] vfio: ABI for mdev display dma-buf operation
> 
>   Hi,
> 
> > No need of flag here. If vGPU driver is not loaded in the guest, there
> > is no surface being managed by vGPU, in that case this size will be
> > zero.
> 
> Ok, we certainly have the same situation with intel.  When the guest driver is not
> loaded (yet) there is no valid surface.
> 
> We should cleanly define what the ioctl should do in that case, so all drivers
> behave the same way.
> 
> I'd suggest that all fields defining the surface (drm_format, width, height, stride,
> size) should be set to zero in that case.
Yeah, it's reasonable. How about the return value? Currently, the ioctl also returns "-ENODEV" in that situation.
 
thanks,
Tina
> 
> cheers,
>   Gerd