[Mesa-dev] [PATCH 1/6] radeonsi: allow DMABUF exports for local buffers

[Marek Olšák]

On Dec 6, 2017 12:34 PM, "Nicolai Hähnle" <nhaehnle at gmail.com> wrote:

On 05.12.2017 20:05, Marek Olšák wrote:

> From: Marek Olšák <marek.olsak at amd.com>
>
> Cc: 17.3 <mesa-stable at lists.freedesktop.org>
> ---
>   src/gallium/drivers/radeon/r600_texture.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/src/gallium/drivers/radeon/r600_texture.c
> b/src/gallium/drivers/radeon/r600_texture.c
> index 2aa47b5..07f7c33 100644
> --- a/src/gallium/drivers/radeon/r600_texture.c
> +++ b/src/gallium/drivers/radeon/r600_texture.c
> @@ -739,22 +739,26 @@ static boolean r600_texture_get_handle(struct
> pipe_screen* screen,
>                         stride = rtex->surface.u.gfx9.surf_pitch *
>                                  rtex->surface.bpe;
>                         slice_size = rtex->surface.u.gfx9.surf_slice_size;
>                 } else {
>                         offset = rtex->surface.u.legacy.level[0].offset;
>                         stride = rtex->surface.u.legacy.level[0].nblk_x *
>                                  rtex->surface.bpe;
>                         slice_size = (uint64_t)rtex->surface.u.legacy.level[0].slice_size_dw
> * 4;
>                 }
>         } else {
> +               /* Buffer exports are for the OpenCL interop. */
>                 /* Move a suballocated buffer into a non-suballocated
> allocation. */
> -               if (sscreen->ws->buffer_is_suballocated(res->buf)) {
> +               if (sscreen->ws->buffer_is_suballocated(res->buf) ||
> +                   /* A DMABUF export always fails if the BO is local. */
> +                   (rtex->resource.flags & RADEON_FLAG_NO_INTERPROCESS_SHARING
> &&
> +                    whandle->type != DRM_API_HANDLE_TYPE_KMS)) {
>

I still don't think this is right. Or at least, it's bound to blow up in
our faces at some point. Though I think we may have talked past each other,
apologies that I haven't made myself clear.

The issues I have in mind are scenarios like this:

1. Buffer allocated in OpenGL.
2. Buffer exported as KMS handle for importing to OpenCL in the same
process.
3. Buffer exported as an FD <-- at this point, the OpenGL and OpenCL
buffers go out of sync because OpenGL re-allocates the buffer but OpenCL
isn't informed.

Or:

1. Buffer allocated in OpenGL.
2. Buffer exported as KMS handle for importing to OpenCL in the same
process.
3. Buffer attempted to be exported as an FD from OpenCL <-- fails because
the buffer is local (has NO_INTERPROCESS_SHARING), and people will be
utterly clueless as to what's going on.

FWIW, I think the patch is good if you drop the whandle->type check so that
we re-allocate unconditionally.


I can remove the check, but buffers are only exported as DMABUF. This patch
isn't just random - it does fix OpenCL interop.

Marek



Cheers,
Nicolai



                        assert(!res->b.is_shared);
>                         /* Allocate a new buffer with PIPE_BIND_SHARED. */
>                         struct pipe_resource templ = res->b.b;
>                         templ.bind |= PIPE_BIND_SHARED;
>                         struct pipe_resource *newb =
>                                 screen->resource_create(screen, &templ);
>                         if (!newb)
>                                 return false;
>
>

-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20171206/4b06f62b/attachment.html>