Support dmabuf in Cuttlefish wayland server

[jmacnak]

Based off of @z-wen-z 's ag/25579081 and migrated from aosp/3173701

Bug: b/353330529
Test: bazel run cuttlefish/package:cvd -- create --host_substitutions=all
and interact with device at https://localhost:1443/

[jmacnak]

Here

[valentineburley]

We've been using this patch in our custom Cuttlefish builds for over a year now, and would very much like to see it merged.

It's been well tested in upstream Mesa CI since last year with our Venus + drm_hwc build, and this year with context-types=venus:cross-domain as well.

[jmacnak]

Forwarded comment: 3rd argument should be buffer_implementation

[jmacnak]

Forwarded comment: this should not be a pointer as the params accumulator "DmabufParams" object is destroyed right after the dmabuf is created.

[jmacnak]

Forwarded comment: drop the PROT_WRITE, the dmabuf's being sent might be read only

[jmacnak]

Hi @valentineburley , I originally just posted this for sharing but it was pointed out that there are some existing issues with the current implementation in this PR. Could you confirm that the dma path was indeed actually being tested even with these issues?

[valentineburley]

Hi @jmacnak, I checked the logs, and the dmabuf path is being exercised. For example, in launcher.log from one of our Mesa CI jobs (with WAYLAND_DEBUG=1), you can see a dmabuf being created and attached:

[4159279.248] zwp_linux_dmabuf_v1@7.create_params(new id zwp_linux_buffer_params_v1@15)
[4159279.280] zwp_linux_buffer_params_v1@15.add(fd 42, 0, 0, 5120, 0, 0)
[4159279.304] zwp_linux_buffer_params_v1@15.create(1280, 1024, 875708993, 0)
[4159279.325]  -> zwp_linux_buffer_params_v1@15.created(new id wl_buffer@4278190080)
[4159279.458] wl_surface@14.attach(wl_buffer@4278190080, 0, 0)

I’m attaching the full launcher.log for reference.