Created attachment 67816 [details]
kernel log without flags

The following commit on current nouveau git master breaks setting a valid
resolution at boot and results in a black screen.

commit 97d6852410a83e413d85649cb2cc10e17d6ee2ab
Author: Ben Skeggs <bskeggs@redhat.com>
Date:   Thu Jul 26 08:51:21 2012 +1000

    drm/nouveau/acpi: move definitions out of nouveau_drv.h

    Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

An interesting thing about this bug is that it can be avoided with adding the
kernel flag nouveau.reg_debug=0x600. With this flag a wrong resolution is set
at boot and the screen does not turn black. The X Server cannot start anyway.

My native resolution is 1366x768. GRUB_GFXMODE is 1360x768x32, since the
greater resolution is not listed in grub's vbeinfo.
nouveau and blob run X with 1366x768.

I will attach a log with and without the flag at commit
97d6852410a83e413d85649cb2cc10e17d6ee2ab.