Bug#855557: primus: gl framedropping isn't handled correctly, apps need a restart to recover

[lkcl]

Package: primus
Version: 0~20150328-4
Severity: important


i am using fvwm2 which is not the cause of the problem, howevver it may
be used to exacerbate an underlying flaw in primus.

the laptop i am using is an amazingly powerful one with a 1060 GTX nvidia
GPU: again, this is not the underlying cause of the problem.

the problem is that if frames are ever dropped (which can occur for
example when moving a window in fvwm2, where it is turned into a
wire-frame in order to save resources) there is no error-recovery
path.  all further GL operations are completely terminated, leaving
whatever application is running as completely frozen with whatever
last graphics operations happened to be underway at the time.

this happens universally on *all* applications.  vlc, chromium,
openscad, glxgears: it does not matter what application it is:
the moment that the window is moved it is guaranteed to cause the
"dropping frame" error message, and that is the last frame ever to
be attempted to be written to screen.

framedropping can also occur intermittently without warning, resulting
*also* in screen freezing.

note that there are no segfaults occurring here (in *any* of the
applications tested), that the rest of the application is perfectly fine:
it's just the opengl-rendered part that is frozen.  in the case of vlc
configured to render with opengl that obviously *means* the entire screen
is frozen, but that's a different matter.


-- System Information:
Debian Release: 7.4
  APT prefers testing
  APT policy: (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.8.0-2-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages primus depends on:
ii  bumblebee                 3.2.1-13
ii  primus-libs               0~20150328-4
ii  socat                     1.7.3.1-2
ii  xserver-xorg-core         2:1.19.0-2.0nosystemd1
ii  xserver-xorg-video-intel  2:2.99.917+git20161206-1

Versions of packages primus recommends:
ii  primus-libs-ia32  0~20150328-4

primus suggests no packages.

-- no debconf information