#dmabuf — Public Fediverse posts

Remember #libobscura ?

The project didn't attract a huge community, but it did teach me stuff so obscure that few people apart from the authors understand it.

So I started writing it down, for everyone's benefit.

If you had questions about #DMABUF, I try to explain it on my #blog :

https://dorotac.eu/posts/DMABUF/

Thanks to all the people who explained it to me. Some parts are really confusing.

(Please report mistakes.)

#linux #kernel #graphics #camera

This scheme would also work for @sima 's #dmabuf file handles (should that become an actual thing) or other in-kernel filesystems.

For example, namespace file descriptors could work the same way although they would need to be uniqified and a lookup routine for them implemented similar to what I did with #pidfs.

WTAF how is #gtk getting n_planes = 1079097857 (consistently the same number across executions) from eglExportDMABUFImageQueryMESA when trying to export a GdkGLTexture containing a #wlroots gles2 rendered scene? 0.o

Wait, that's not just some random number, that's the low 32 bits of the modifier field!!

OHHHH SHIT it's not mentioned in the extension spec at all but with current Mesa code, modifiers is expected to be AN ARRAY of per-plane entries. The spec only says that the stuff passed to the next step eglExportDMABUFImageMESA is expected to be arrays. #egl #mesa3d #dmabuf

Reported: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12771