Debugging Gnome-Shell not starting

[Ulrik Sverdrup <ulrik sverdrup gmail com>]

Hi,

I want to use and try gnome-shell. I have built it successfully with
jhbuild, and I can run in Xephyr where it is totally fluid even on my
old hardware (ATI 9200 something radeon).

I need help to debug why gnome-shell doesn't start when I try to run
it ./gnome-shell --replace

What happens is that all window disappear, only the desktop background
is visible, gnome shell is loading or doing some kind of work, then
nothing happens. The problem is also that the X server won't respond
to any key presses (mouse pointer will move); I can't switch VTs, I
can't kill it with ctrl-alt-bcksp. (I force restart at this point,
after waiting 1-5 minutes)

I have compared the verbose logs from running in Xephyr and running
--replace, and found that where the "crashing" log ends, Xephyr tells
this on the next line:

drmWaitVBlank returned -1, IRQs don't seem to be working correctly.
Try adjusting the vblank_mode configuration parameter.

This means DRM/DRI initialization is done at this point? Anyway, I
have configured vblank_mode to 0 after that and tried again; the
message will disappear from the Xephyr log, but the --replace'd
gnome-shell still won't get past this point. So that means it won't
wget past a point where DRM/DRI is being initialized.

I don't know how to go further with this. Metacity works with
compositing, switching on the fly works well. Metacity compositing is
slow however, but Gnome-Shell in Xephyr is really fluid (but has a
tint of Yellow to the graphics!), so the hardware can run gnome-shell
fluidly.

Thank you for any help in debugging this. As the log file for
gnome-shell contains absolutely nothing from Xorg, I don't think that
log file helps; I rather need help where to look and what to log next
time I try.

Regards.
Ulrik