[Bug 32511] New: glDrawPixels broken on savage

[bugzilla-daemon@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=32511

           Summary: glDrawPixels broken on savage
           Product: Mesa
           Version: git
          Platform: x86 (IA32)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/Savage
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: bugzi09.fdo.tormod@xoxy.net


Created an attachment (id=41267)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=41267)
full backtrace in savageWriteRGBASpan_565()

The drawpix demo draws pixels spread around the screen instead of inside the
window. Each line drawn (194 pixels) get displayed in a cluster, but not as a
line. Only every 6th "line" get displayed, starting from the lower right of the
screen, going left, then up (see drawpix-many.png).

The cluster is divided in 4 squares of 8 times 8 pixels, where the first and
fourth square is not complete. Each square is drawn from left to right, then
from top to bottom. Square are drawn from left to right within a cluster. (See
drawpix-line.png).

I have tracked the drawing in mesa down to where it writes each pixel into the
renderbuffer in savageWriteRGBASpan_565(), see the full backtrace in
write_rgba-backtrace.gdb.

This is with latest git. I think I have seen similar corruption using the
antspotlight screensaver since a long time ago, and I never tried drawpix
before so this can be an old bug. The bug reporter of the downstream Ubuntu bug
says drawpix worked fine in Ubuntu 8.04 which had mesa 7.0.3.

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