This makes two Via motherboards that have given me no end of grief... it's the last time I'm ever going non-Intel. But until I get a new mobo, I'm trying to get my AGP working. Using NvAGP hasn't worked for me, and neither has AGPGART. Since my chipset isn't supported by NvAGP, I've been mostly messing with AGPGART.
I get complete lockups as soon as X starts -- sometimes before I even log in, at the xdm screen, sometimes just after my WM starts. I read that having fast AGP writes and SBA enabled can lead to instability. I disabled fast writes in my BIOS, but there was no section related to SBA. The NV docs says to extract the drivers from the .run file and edit os-registry.c, which I did. SBA *should* be disabled. I even went into /etc/modprobe.conf and added this line as someone suggested: "options nvidia NVreg_EnableAGPSBA=0 NVreg_EnableAGPFW=0" but that didn't work either.
Here's what a cat /proc/driver/nvidia/agp/status produces:
Driver: AGPGART (inactive)
AGP Rate: 8x
Fast Writes: Disabled
Anyone know how to definitively disable SBA? I don't want to give up on AGP until I've tried disabling that first. If you have advice on getting the P4x400 to work with the GF4 those are welcome too.