Re: linux-c7 and opengl apps?

On Fri, Oct 5, 2018 at 11:21 PM, Theron <theron.tarigo_at_gmail.com> wrote:
> % /compat/linux/opt/VirtualGL/bin/glxinfo | grep OpenGL
> libGL error: MESA-LOADER: failed to retrieve device information

Do you have linsysfs mounted?

Try reading /compat/linux/sys/class/drm/card0/device/uevent.

Mesa won't retrieve device information without linsysfs.
I wrote the linsysfs patch that exposed the info there so that recent 
Mesa would work :)
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222375
(Wow, that was a year ago… interesting note from there: you might 
need to set LIBGL_DRI3_DISABLE=1 for Linux apps)

Also, what's with the "/opt/VirtualGL"? Are you using mesa from 
linux-c7 or something… weird?

> This problem has existed forever.  I am not sure it is actually a 
> fault in Linux emulation, as these very same symptoms ("failed to 
> retrieve device information" message, console freeze) existed back in 
> FreeBSDDesktop/freebsd-base-graphics days when attempting to run 
> purely FreeBSD OpenGL apps.  At the time the workaround was a patch 
> to Mesa's GPU detection; the underlying kernel problem wasn't 
> addressed.

There was a somewhat related issue (but not the same one, FreeBSD and 
Linux versions of mesa/libdrm use different mechanisms to get device 
info).
Mostly affected Wayland-EGL clients — they would try to access 
/dev/dri/card408 instead of /dev/dri/card0, fail to get info and fall 
back to software rendering.
I fixed it a while ago: 
https://gitlab.freedesktop.org/mesa/mesa/commit/db8519a369261cdedda50852facc45616d4eba28

But I never saw console freezes when Mesa couldn't properly detect the 
GPU o_0