Would someone please point me to some reasonably current instructions for getting greater than 1024x768 video resolution for a CentOS 6 guest on a CentOS 6 KVM/qemu host? When I search online I find stuff from 2009 and 2010 saying, "For details see ...," and linking to a URL that no longer exists, or pages that say, "You need to switch from VNC to Spice," and giving a long list of out-of-date instructions for doing so. (With virt-manager it takes 2 clicks to do that. Of course it doesn't help -- still maxes out at 1024x768.)
I've found that I can just append "vga=0x380" to the kernel command line and see Plymouth come up with the full graphical boot screen in the correct 1440x900 resolution, but as soon as gdm starts up, the display scrambles. I find suggestions to generate an xorg.conf file, but no mention of what to put in it. I can run "Xorg -configure", but the resulting file contains nothing about video modes, so it's not apparent what needs to be added.
I find it particularly annoying that a Windows 7 guest can set any resolution I want up to 2560x1600, but a Linux guest can't go higher than 1024x768.