RE: [PATCH 00/11] Add support for Blob resources feature

["Kasireddy, Vivek" <vivek.kasireddy@intel.com>]

Hi Gerd,
While looking at the Qemu UI code, I noticed that there is a Blit operation
performed to copy the Guest FB (texture) into a Host buffer before it is presented
to the Host compositor. I was wondering if there are any elegant ways to
eliminate this Blit to further the goal of absolute zero-copy. One idea that I am 
familiar with involves the usage of this extension:
https://www.khronos.org/registry/EGL/extensions/WL/EGL_WL_create_wayland_buffer_from_image.txt

However, I do realize that this is very Wayland specific but we are also going to need
to add explicit sync support which is currently only available in upstream Weston. 
I did try adding explicit sync support to GTK but the maintainers are not particularly
thrilled about it:
https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/3410

Any other ideas as to how to eliminate that Blit cleanly?

Thanks,
Vivek

> -----Original Message-----
> From: Kasireddy, Vivek <vivek.kasireddy@intel.com>
> Sent: Tuesday, March 30, 2021 8:10 PM
> To: qemu-devel@nongnu.org
> Cc: Kasireddy, Vivek <vivek.kasireddy@intel.com>; Gerd Hoffmann
> <kraxel@redhat.com>; Marc-André Lureau <marcandre.lureau@redhat.com>; Kim,
> Dongwon <dongwon.kim@intel.com>; Zhang, Tina <tina.zhang@intel.com>
> Subject: [PATCH 00/11] Add support for Blob resources feature
> 
> Enabling this feature would eliminate data copies from the resource object in the Guest to
> the shadow resource in Qemu. This patch series however adds support only for Blobs of
> type VIRTIO_GPU_BLOB_MEM_GUEST with property
> VIRTIO_GPU_BLOB_FLAG_USE_SHAREABLE.
> 
> Most of the patches in this series are a rebased, refactored and bugfixed versions of Gerd
> Hoffmann's patches located here:
> https://gitlab.freedesktop.org/virgl/qemu/-/commits/virtio-gpu-next
> 
> TODO:
> - Enable the combination virgl + blob resources
> - Add support for VIRTGPU_BLOB_MEM_HOST3D blobs
> 
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
> Cc: Dongwon Kim <dongwon.kim@intel.com>
> Cc: Tina Zhang <tina.zhang@intel.com>
> 
> Vivek Kasireddy (11):
>   ui: Get the fd associated with udmabuf driver
>   ui/pixman: Add qemu_pixman_to_drm_format()
>   virtio-gpu: Add udmabuf helpers
>   virtio-gpu: Add virtio_gpu_find_check_resource
>   virtio-gpu: Refactor virtio_gpu_set_scanout
>   virtio-gpu: Refactor virtio_gpu_create_mapping_iov
>   virtio-gpu: Add initial definitions for blob resources
>   virtio-gpu: Add virtio_gpu_resource_create_blob
>   virtio-gpu: Add helpers to create and destroy dmabuf objects
>   virtio-gpu: Add virtio_gpu_set_scanout_blob
>   virtio-gpu: Update cursor data using blob
> 
>  hw/display/meson.build                      |   2 +-
>  hw/display/trace-events                     |   2 +
>  hw/display/virtio-gpu-3d.c                  |   3 +-
>  hw/display/virtio-gpu-base.c                |   3 +
>  hw/display/virtio-gpu-udmabuf.c             | 276 +++++++++++++
>  hw/display/virtio-gpu.c                     | 423 +++++++++++++++-----
>  include/hw/virtio/virtio-gpu-bswap.h        |  16 +
>  include/hw/virtio/virtio-gpu.h              |  41 +-
>  include/standard-headers/linux/udmabuf.h    |  32 ++
>  include/standard-headers/linux/virtio_gpu.h |   1 +
>  include/ui/console.h                        |   3 +
>  include/ui/qemu-pixman.h                    |   1 +
>  scripts/update-linux-headers.sh             |   3 +
>  ui/meson.build                              |   1 +
>  ui/qemu-pixman.c                            |  35 +-
>  ui/udmabuf.c                                |  40 ++
>  16 files changed, 772 insertions(+), 110 deletions(-)  create mode 100644
> hw/display/virtio-gpu-udmabuf.c  create mode 100644 include/standard-
> headers/linux/udmabuf.h
>  create mode 100644 ui/udmabuf.c
> 
> --
> 2.26.2