Garbled screen for KMS and ATI Radeon X800

[Christoph Frieben]

After building wayland, mesa, cairo-gl, and libxkbcommon (git version
of 2010-11-12), compositor and clients runs nicely in a window on top
of a GNOME desktop under Fedora 14 (kernel-2.6.35.8-55.fc14.x86_64).
However, when started in a VT, the screen shows a garbled pattern.
Moving the mouse has no effect. It is possible though to abort the
compositor and to get dropped to the shell. Issue occurs for an ATI
Radeon X800 (Chipset: "ATI Radeon X800 SE (R430) (PCIE)" (ChipID =
0x554e)). glxinfo reports

OpenGL vendor string: X.Org R300 Project
OpenGL renderer string: Gallium 0.4 on R430
OpenGL version string: 2.1 Mesa 7.10-devel
OpenGL shading language version string: 1.20

Any clues how to get wayland up and running in KMS?