[PATCH v16 5/6] vfio: ABI for mdev display dma-buf operation

[Zhang, Tina]

> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson at redhat.com]
> Sent: Tuesday, November 7, 2017 4:37 AM
> To: Gerd Hoffmann <kraxel at redhat.com>
> Cc: Zhang, Tina <tina.zhang at intel.com>; Tian, Kevin <kevin.tian at intel.com>;
> Daniel Vetter <daniel.vetter at ffwll.ch>; intel-gfx at lists.freedesktop.org;
> joonas.lahtinen at linux.intel.com; linux-kernel at vger.kernel.org;
> zhenyuw at linux.intel.com; chris at chris-wilson.co.uk; kwankhede at nvidia.com;
> Lv, Zhiyuan <zhiyuan.lv at intel.com>; daniel at ffwll.ch; intel-gvt-
> dev at lists.freedesktop.org; Wang, Zhi A <zhi.a.wang at intel.com>
> Subject: Re: [PATCH v16 5/6] vfio: ABI for mdev display dma-buf operation
> 
> On Mon, 06 Nov 2017 10:05:34 +0100
> Gerd Hoffmann <kraxel at redhat.com> wrote:
> 
> >   Hi,
> >
> > > > I thought we had agreed to make this behave similar to
> > > > VFIO_GROUP_GET_DEVICE_FD, the ioctl would take a __u32 dmabuf_id
> > > > and return the file descriptor as the ioctl return value.  Thanks,
> > >
> > > If we follow VFIO_GROUP_GET_DEVICE_FD, we would lose flags
> > > functionality.
> > > Zhi and Zhenyu, how do you think about it?
> >
> > The ioctl is simple enough that not having flags should not be a
> > problem I think.
> >
> > Also note that dmabuf_id is received using the PLANE_INFO ioctl, so
> > should the need arise to negotiate something in the future chances are
> > high that it can be done using the PLANE_INFO ioctl flags.
> 
> Right, the ioctl is "get fd for thing" so we have control of "thing".
> I think we had this same discussion on v15.  Thanks,
Then, OK. Thanks.

BR,
Tina
> 
> Alex