Bug#558786: X.org radeon driver breaks KDE when radeon.ko is present
this actually has a deeper impact.
DRI1 is used by the radeon X.org driver when radeon.modeset=0
(linux-2.6.32) but then KDE is horribly broken (scrolling in any KDE
application gives render errors). Forcing XAA doesn't work (EXA is
always used). This is only solved by preventing radeon.ko from being
loaded. This issue is also present in linux-2.6.31.
DRI2 is tried by the radeon X.org driver when radeon.modeset=1 (which
works great on the VT). But since libdrm doesn't support that in
unstable, it breaks X completely (KDM doesn't show any useful screen,
I didn't test compiling libdrm and mesa myself (didn't want to mess
with my system). Thus, any DRI is currently impossible on my Radeon
Mobility HD 2400 XT (RV610 / M7). However, not using radeon.ko and
thus only 2D works fine :)
I would really like to test libdrm-radeon, too.