Why we didn't use embedded gem object for virtio gpu when making ttm bo a gem bo subclass?

[lepton]

Hi Gerd,

Thanks for your reply. I was aware of that change, but need a fix for
5.4 kernel as a temp solution for now.
If the reason is just that you will move away from ttm soon,then I
guess a CL like http://crrev.com/c/3092457 should
work for 5.4, just hope I don't miss anything else.

Thanks!

On Sun, Aug 15, 2021 at 9:46 PM Gerd Hoffmann <kraxel at redhat.com> wrote:
>
> On Fri, Aug 13, 2021 at 12:42:51PM -0700, lepton wrote:
> > Hi Gerd,
> >
> > We found a bug in 5.4 kernel and virtgpu_gem_prime_mmap doesn't work
> > because it references vma_node in gem_base object while ttm code
> > initialized vma_node in tbo.base object. I am wondering, in your
> > original serial:
> > https://patchwork.kernel.org/project/dri-devel/cover/20190805124310.3275-1-kraxel@redhat.com/
> > (drm/ttm: make ttm bo a gem bo subclass), why you changed to use
> > embedded gem object for most gpu drivers but skipping virtio gpu? Is
> > there some specific reason?
>
> commit c66df701e783bc666593e6e665f13670760883ee
> Author: Gerd Hoffmann <kraxel at redhat.com>
> Date:   Thu Aug 29 12:32:57 2019 +0200
>
>     drm/virtio: switch from ttm to gem shmem helpers
>
> HTH,
>   Gerd
>