Bug 71887 - Garbled output when rendering to a framebuffer object
Summary: Garbled output when rendering to a framebuffer object
Status: RESOLVED NOTABUG
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/Gallium/r600 (show other bugs)
Version: 9.2
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
URL:
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Depends on:
Blocks:
 
Reported: 2013-11-21 19:07 UTC by Victor Luchits
Modified: 2013-12-24 19:47 UTC (History)
0 users

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Attachments
3.11 screenshot (204.00 KB, image/jpeg)
2013-11-21 19:07 UTC, Victor Luchits
Details
3.12 screenshot (264.00 KB, image/jpeg)
2013-11-21 19:07 UTC, Victor Luchits
Details
3.12 + Mesa-dev (Intel) screenshot (124.00 KB, image/jpeg)
2013-11-22 07:36 UTC, Victor Luchits
Details

Description Victor Luchits 2013-11-21 19:07:17 UTC
Created attachment 89601 [details]
3.11 screenshot

Hardware: AMD HD 5770
Motherboard: MSI 790FX-GD70

Upon updating to 3.12 Linux kernel noticed that render-to-texture (FBO) in Warsow has regressed.

In 3.12 the target texture seems to contain random but consistent region of video card's texture memory: the blueish pattern on the screenshot definitely looks like a normalmap.

We could not reproduce the bug on another machine with AMD HD 67xx.
Comment 1 Victor Luchits 2013-11-21 19:07:37 UTC
Created attachment 89602 [details]
3.12 screenshot
Comment 2 Alex Deucher 2013-11-21 20:01:08 UTC
Did you only update your kernel or did you also update mesa?
Comment 3 Victor Luchits 2013-11-22 07:09:42 UTC
No I didn't. Do you recommend updating to 9.3/development version of Mesa to see if the bug can not be reproduced there?
Comment 4 Michel Dänzer 2013-11-22 07:27:30 UTC
If you only changed the kernel, can you bisect?
Comment 5 Victor Luchits 2013-11-22 07:36:32 UTC
Created attachment 89622 [details]
3.12 + Mesa-dev (Intel) screenshot

Same spot on Intel Ivybridge Mobile (HD 4000). Looks identical both in Mesa 9.3 and Mesa 10-dev.
Comment 6 Victor Luchits 2013-11-22 07:38:25 UTC
Ok, I will update to Mesa 10-dev when I get back home and if it doesn't help, I'll try to bisect.
Comment 7 Victor Luchits 2013-11-23 10:22:00 UTC
Ok, after mucho fruitless bisecting all I was able to figure out is that the bug is reproducable on stock 3.11+ kernels but _not_ on 3.11 kernel shipped with Ubuntu 13.10.
Comment 8 Victor Luchits 2013-12-24 19:47:01 UTC
Turns out the issue was related to how glGenRenderbuffersEXT generated id numbers for framebuffers. Apparently some kernel change affected the outcome and in combination with bug in the game code caused the reported issue.

Resolving as NOTABUG.


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