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

[Zhang, Tina]

> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx]
> Sent: Tuesday, November 7, 2017 4:37 AM
> To: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> Cc: Zhang, Tina <tina.zhang@xxxxxxxxx>; Tian, Kevin <kevin.tian@xxxxxxxxx>;
> Daniel Vetter <daniel.vetter@xxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx;
> joonas.lahtinen@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> zhenyuw@xxxxxxxxxxxxxxx; chris@xxxxxxxxxxxxxxxxxx; kwankhede@xxxxxxxxxx;
> Lv, Zhiyuan <zhiyuan.lv@xxxxxxxxx>; daniel@xxxxxxxx; intel-gvt-
> dev@xxxxxxxxxxxxxxxxxxxxx; Wang, Zhi A <zhi.a.wang@xxxxxxxxx>
> 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@xxxxxxxxxx> 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.ÂÂThanks,
> > >
> > > 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