https://bugs.freedesktop.org/show_bug.cgi?id=28016
--- Comment #7 from Grzegorz Kowal astronomo@op.pl 2010-05-10 06:29:42 PDT --- Basically, I am just booting the kernel. The screen is corrupted since the initialization of the KMS (bounch of white dots on black background, it looks like each line is shifted horizontally). When I log in using ssh, however, everything seems to work fine.
Once I start the X server I am getting the soft lockup. The screen flickers a few times, the server seems to restart ending with the distorted image of kdm background. I can post the images if necessary.
After reverting 6b8b1786a8c29ce6e32298b93ac8d4a18a2b11c4 everything works fine. There is no screen corruption after the KMS initialization and the X server works fine. Obviously, the amount of accessible VRAM is reduced from 1024MB to 256MB then.