Can't set resolution for console

[andras.lorincz@gmail.com]

I'm using Sid with AIW Radeon, kernel 2.6.9 compiled with frame buffer support 
and want to change the text mode resolution. I've tried in grub to pass 
kernel parameter vga=791, but after the grub menu is listed and the kernel 
begins to load,  the screen blanks until the kdm starts. Another try was to 
set vga=ext, that has some effect: after grub menu is listed, the kernel 
begins to load and the resolution is changed properly, but while the system 
loads, at a moment the resolution is changed back to 80x25 before kdm starts.

How should I handle it?