Corrupted display after Debian 6.0.2.1 installation on iMac G5

[Aaro Koskinen <aaro.koskinen@iki.fi>]

Hello,

I finally decided to switch from Mac OS X to Debian on my
G5 iMac. I downloaded the netinst CD image, and the
installation worked just fine.

Unfortunately, now when I reboot the installed system, it's
unusable due to corrupted display (there's just some
psychedelic noise, you barely see any text). The boot and
console display are fine up to the point when the DRM kernel
modules are loaded, I think.

Is there any way I could disable the DRM and other "advanced"
graphics stuff from the yaboot prompt, and use just the bare
frame buffer?

BTW, I think the HW model is M9250LL/A.

A.