https://bugs.freedesktop.org/show_bug.cgi?id=48131
Bug #: 48131 Summary: Very large 2D texture is sometimes corrupted Classification: Unclassified Product: Mesa Version: unspecified Platform: Other OS/Version: All Status: NEW Severity: normal Priority: medium Component: Drivers/DRI/R600 AssignedTo: dri-devel@lists.freedesktop.org ReportedBy: bjacob@mozilla.com
This WebGL testcase just creates a huge blank texture and draws a quad with it:
http://people.mozilla.org/~bjacob/webgltexture2D5k.html
You should see only black. But here I occasionally see some corruption with vertical yellow stripes on a rectangular part of the image. Reloading the page a few times makes the problem go away.
The testcase uses webgl.texImage2D with null pixel data, which causes the browser to calloc() a buffer and pass it to glTexImage2D. So it's not just an uninitialized texture. The application is doing what's right to properly initialize the texture with zero'd image data.
If there is any risk that this might be exposing uninitialized texture memory, then please treat this as a high priority, as we'd have to find a work around.
FWIW, on a different proprietary platform, this does expose video memory and forced us to artificially limit the max texture size to 4k.