Bug 93203

mesa: 18f8da7865ddc27e4bb17f935c826f803bdfd5ba (master 11.2.0-devel)

$ ./bin/gl30basic -auto
Probe color at (0,0)
  Expected: 1.000000 0.000000 1.000000
  Observed: 0.478431 0.094118 0.282353
  from glClearBufferfv(GL_FRONT) failed.
Probe color at (0,0)
  Expected: 0.000000 1.000000 0.000000
  Observed: 0.478431 0.094118 0.282353
  the front buffer from glClearBufferfv(GL_FRONT_AND_BACK) failed.
PIGLIT: {"result": "fail" }


2b676570960277d47477822ffeccc672613f9142 is the first bad commit
commit 2b676570960277d47477822ffeccc672613f9142
Author: Dave Airlie <airlied@redhat.com>
Date:   Fri Oct 9 01:38:08 2015 +0100

    gallium/swrast: fix front buffer blitting. (v2)
    
    So I've known this was broken before, cogl has a workaround
    for it from what I know, but with the gallium based swrast
    drivers BlitFramebuffer from back to front or vice-versa
    was pretty broken.
    
    The legacy swrast driver tracks when a front buffer is used
    and does the get/put images when it is mapped/unmapped,
    so this patch attempts to add the same functionality to the
    gallium drivers.
    
    It creates a new context interface to denote when a front
    buffer is being created, and passes a private pointer to it,
    this pointer is then used to decide on map/unmap if the
    contents should be updated from the real frontbuffer using
    get/put image.
    
    This is primarily to make gtk's gl code work, the only
    thing I've tested so far is the glarea test from
    https://github.com/ebassi/glarea-example.git
    
    v2: bump extension version,
    check extension version before calling get image. (Ian)
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91930
    
    Cc: <mesa-stable@lists.freedesktop.org>
    Signed-off-by: Dave Airlie <airlied@redhat.com>

:040000 040000 1726a5f7f01d9ae1fc76de431bb24cce16cf69ee 75f18ded95766bac58d0c37c96ffa071a4a32071 M	include
:040000 040000 ee333146b90c837460ceab252445e3b38fc528d5 dc0656326c3fb9750fda1f6d3e75aeed99003bc6 M	src
bisect run success