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.