DMA-BUF Feedback Support For Wayland Lands In Mesa 22.0's EGL Code

Landing in Mesa on Black Friday was DMA-BUF Feedback support within the EGL code as another important step forward for Wayland.

Introduced earlier this week was Wayland Protocols 1.24 and the primary addition to that collection of protocols is DMA-BUF feedback support. The DMA-BUF "feedback" support is important for Wayland multi-GPU systems where needing to know more information about the GPU device used by the compositor and for being able to efficiently exchange buffers between the secondary and primary GPUs.

The DMA-BUF feedback support for Wayland's DMA-BUF protocol adds the concept of the "main device" and "tranches" that specify format/modifier pairs for ensuring the buffers can be exchanged in a compatible manner for direct scan-out.

On Friday this Mesa Git merge happened for the code that has been under review for the past five months. This code gets DMA-BUF Feedback support wired into the EGL code for Mesa 22.0.

Making use of this protocol addition on the compositor side is already pending for wlroots and Weston while other compositors should follow suit in the near future.