Maybe this is the cause of the crash:
I am running a NVidia fx5600 APG8x Gfx-card.
Steps to Reproduce:
1. SiS 746 Mainboard
2. enable /dev/agpgart (AGP Support) in kernel
System crashes hard upon trying to start Xfree
start xfree (without /dev/agpgart it does)
http://www.ussg.iu.edu/hypermail/linux/kernel/0304.3/0371.html and followups
might explain the cause. Maybe there should be a warning in the kernel doc.
I don't think that's the problem, that email was in response to a patch that we don't use. The best thing I can tell you is try to use the nvidia driver internal agp support (but that may only work on nvidia chipsets), or try upgrading to 2.6. I just closed a bug earlier saying we have no plans to backport agp3.0/8x support to gentoo-sources, so I wouldn't hold your breath about getting support from gentoo-sources. We haven't historically documented what does and doesn't work in kernels since that is likely to change from week to week and day to day.