[Bug 37971] System freeze when using agpgart

John Lenz lenz at cs.wisc.edu
Tue Apr 4 05:19:45 UTC 2006

Public bug reported:

Affects: linux-source-2.6.12 linux-image-2.6.12-9-amd64-generic (Ubuntu)
       Severity: Normal
       Priority: (none set)
         Status: Unconfirmed

Running Breezy Badger

I have a dual monitor setup, with a Radeon 9200 AGP (RV280) and Nvidia
RIVA TNT2 Model 64 PCI card.  What happens is if I try and run both
video cards at 1280x1024, about 3-4 seconds after logging in the system
completly freezes... Ctrl-Alt-Backspace no longer restarts X, mouse
doesn't move, numlock doesn't work anymore, etc....

If I run the TNT2 PCI card at 1024x768 resolution, everything works just
fine.  Also, if I block agpgart (and radeon, and drm) modules from
loading into the kernel (by sticking some stuff into /etc/modules.d), I
can run both video cards at 1280x1024.

So, without agpgart loaded, both run fine at 1280x1024, but with agpgart
loaded I can run PCI card at 1024x768 but it freezes at 1280x1024.  I
looked through kern.log, but no oopses are in there. Here is some output
from kern.log when loading agpgart

pr  3 23:07:13 localhost kernel: [   16.814772] agpgart: Detected AGP bridge 0
Apr  3 23:07:13 localhost kernel: [   16.819005] agpgart: AGP aperture is 128M @ 0xe0000000
Apr  3 23:07:23 localhost kernel: [   64.092212] agpgart: Found an AGP 3.0 compliant device at 0000:00:00.0.
Apr  3 23:07:23 localhost kernel: [   64.092225] agpgart: Putting AGP V3 device at 0000:00:00.0 into 4x mode
Apr  3 23:07:23 localhost kernel: [   64.092250] agpgart: Putting AGP V3 device at 0000:01:00.0 into 4x mode

0000:01:00.0 is the AGP card, and 0000:00:00.0 is the PCI card.  My first guess is some sort of buffer overflow in agpgart, when using the higher resolution.  I find it odd that agpgart is setting both cards up, when only one is AGP and the other is a normal PCI card.
System freeze when using agpgart

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