X login screen uses wrong resolution with viewport
 

Debian Linux Sid i386
Kernel 2.6.11-custom-k7, debian patched
XFree86 4.3.0.1 (Debian 4.3.0.dfsg.1-13 20050513091634)
ATI RADEON 8500 AIW (R200 4242), fglrx 8.12.10
Proview PS series Monitor, capable of resolutions up to 1600x1200.

I will refrain from posting my entire X config and log here. Nothing unusual, no errors.

With the configuration above, I am trying to set up X Windows using a default resolution of 800x600 but with the capability to switch to higher resolutions.

Concerning the Modes entry of the Display SubSection, XF86Config-4(5x) states "The first valid mode in this list will be the default display mode for startup."
However I believe I have found this to be incorrect. Despite X allowing all 4x3 resolutions from 640x480 to 1600x1200, if these are specified thusly...

Modes "800x600" "640x480" "1600x1200" "1280x1024" "1152x864" "1024x768"

...the resolution used on the login screen is 1600x1200 but with a viewport of, I believe 800x600. This creates the phenomenon where you can scroll around a virtual screen. But this is wrong! It should be using 800x600, but instead, with any higher resolution specified afterwards, it will favour the highest resolution with a viewport.

I am forced to only specify 800x600 and "640x480" to avoid this behaviour.

Has anyone else encountered this before? Any suggestions?

If you have used fglrxconf to do the configuration you might have selected this behaviour from an option that fglrxconf gives during the configuration. Just reconfigure it and press n (no) when it prompts you for this.

Thanks for replying, but I tried what you said and it did not change the problem. This is probably a lower-lying problem with the X server, as I think it happens on another machine too.
Perhaps the X.org coming to Debian Unstable will fix this.