Comment 27 for bug 34144

@Neil Wilson
Hi,
We only took the route of deleting the module because I'm using a LiveCD and so could not blacklist and reboot with that change saved. It's just a workaround because I don't have an Ubuntu install at present (although I will install if needed).

At this point, I think there are two problems.
Problem 1: If both the amd64_agp and the sis_agp drivers are loaded, then there is a conflict that prevents the size of the agp aperture from being identified correctly (4M rather than the setting in the BIOS, which is 128M for me); dri is not enabled.
Problem 2: If only the amd64_agp driver is used, then dri works too, BUT the system also produces a steady stream of APIC errors which are written to the syslog at varying rates (more frequently for me than for awen, it seems).

Do you happen to see the APIC errors in your syslog, too?

Since the kernel instructions indicate that both amd64_agp and a chipset specific module are needed for amd64 systems, maybe it's not too surprising that there is some kind of adverse effect to not using sis_agp at all. (I'm referring to the instruction that are visible from the curses menuconfig interface, I'm actually not sure where they are located to make a link to show what I'm talking about).