Hi,
On 04.04.2017 09:23, Luke Kenneth Casson Leighton wrote:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848895
there's a really strange and comprehensively cross-application
intermittent bug that's only occurring on opengl-based applications,
that's been introduced some time in the past year. to be absolutely
honest nobody's even sure it's actually opengl-related or whether it's
x11 related, but it's so weird that it's really hard to pin down.
the above bugreport on debian with chromium-browser is *just one* of
the occurrences, but it occurs with glxgears, openscad and a whole
stack of other applications.
the simplest 100% guaranteed way discovered so far to reproduce the issue is:
* install debian / testing
* install fvwm2
* set up fvwm2 to use "wireframe" for "resize window"
* run glxgears
* go ahead and resize the glxgears window with a mouse
that is *guaranteed* to result in glxgears "freezing". the only known
guaranteed way to "recover" it is to switch to text console
(ctrl-alt-f1) followed by switching back to X11 (ctrl-alt-f7).
That's pretty good clue.
there are various teams trying to "fix" this bug, believing it to be
the fault of their application. this includes the chromium-browser
team. what they've managed to do so far is to simply... avoid *most*
circumstances under which the lock-up occurs... but all that happens
is that the processor running the application goes into multi-tasking
meltdown... *and then still* gets a lock-up.
it doesn't matter what underlying hardware is used: intel graphics,
nvidia, ATI. it doesn't even matter if you use optirun: that *still*
results in a lockup although there you get a rather useful error
message indicating that the GPU is trying to do its job, but reports
constantly that the frame had to be dropped.
anyway, apologies: nobody whose applications are affected by this
really has a clue where the *actual* bug is so i am escalating it down
the chain of library dependencies, making people aware. it could be
X11, it could be mesa, we just don't know.
Does it happen only with the old, non-compositing window managers like
FVWM2, or also with something newer?
Does DRI2 vs. DRI3 have any effect on it?
- Eero
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