TIL: Mesa 17 downgraded OpenGL support for my old netbook
TL;DR: if you run GNU , have old Intel-based graphics, and start having OpenGL issues, this might interest you =)
I have an old-ish eeePC netbook running Debian Sid with Plasma desktop (what else? ;)
Up until the Stretch release, everything was fine. Soon after that, Mesa was upgraded from 13.x to 17.x, and some time later, I realized that Plasma didn't have compositing anymore (i.e. desktop effects weren't working).
Some investigation led me to realize that the Mesa upgrade was the culprit. With Mesa 13.x, the reported OpenGL version was 2.1. With Mesa 17.1.4, reported OpenGL version was 1.4, which Plasma (Kwin) sees as not enough for its compositing.
Also, mpv couldn't use the OpenGL video output.
While compiling info to open a bug report to Debian, the very very helpful people at #email@example.com pointed me to this post on Mesa's mailing list explaining the issue (the hardware doesn't really support OGL 2+).
Thanks, Debian people, especially tosky!
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