Everytime I start X, drm gets disabled, here is a snippet from /var/log/Xorg.0.log:
(II) RADEON(0): [drm] installed DRM signal handler
(WW) RADEON(0): [agp] AGP not available
(EE) RADEON(0): [agp] AGP failed to initialize. Disabling the DRI.
(II) RADEON(0): [agp] You may want to make sure the agpgart kernel module
is loaded before the radeon kernel module.
(II) RADEON(0): [drm] removed 1 reserved context for kernel
(II) RADEON(0): [drm] unmapping 8192 bytes of SAREA 0xf802e000 at 0xb7183000
(II) RADEON(0): [drm] Closed DRM master.
(II) RADEON(0): RADEONRestoreMemMapRegisters() :
(II) RADEON(0): MC_FB_LOCATION : 0xe7ffe000 0x1fff0000
(II) RADEON(0): MC_AGP_LOCATION : 0xffffffc0
(==) RADEON(0): Backing store disabled
(WW) RADEON(0): Direct rendering disabled
I am on gentoo-sources 2.6.31-r6 with xf86-video-ati-6.12.4 and xorg-server-1.6.5-r1.
I have entered the appropriate kernel modules in a correct order in /etc/modules.autoload.d/kernel-2.6, to no avail. Manually removing and reloading modules does not work either.
It's a kernel issue, the X driver can't do anything about it.
If it's a newer card with a PCIe based GPU,
Option "BusType" "PCIE"
may be a feasible workaround.