Wayland Protocols 1.24 Released With Improvement To DMA-BUF Protocol For Multi-GPUs

Wayland Protocols 1.24 is out today as the latest revision to this official collection of the Wayland protocols/specifications. Notable with the 1.24 revision is the introduction of wp_linux_dmabuf_feedback.

Added initially as an "unstable" addition for Wayland-Protocols 1.24 is wp_linux_dmabuf_feedback as the "feedback" addition to the Linux DMA-BUF protocol. This is particularly useful for modern multi-GPU setups where needing to know about the GPU device in use by the compositor and the semantics around it such as if using the secondary GPU that DMA-BUF can still exchange buffers with the main GPU and in a compatible format.

The DMA-BUF feedback object introduces the notion of the "main device" and "tranches" as a list of format/modifier pairs that are compatible with the target device. With a tranche it is also indicated whether the buffers allocated with that format/modifier pair can be used for direct scan-out purposes. For Wayland-Protocols 1.24 the addition is marked as zwp_linux_dmabuf_feedback_v1.

Besides improving the DMA-BUF allocation handling for multi-GPU setups, Wayland Protocols 1.24 clears out its Autotools build system support and now relies exclusively on Meson. Plus there are various other minor fixes included as part of this release. The small list of changes can be found on the mailing list.