I would like to setup a multiseat configuration on CentOS 6.3 (two video cards, two keyboards, two mice, two monitors) and have hardware accelerated 3D on both monitors. 3D HW acceleration rules out Xephyr. I saw somewhere that recent versions of GDM (3.3 and newer?) don't support multiseat, so do I have to install KDM to make this work? If I just create a duplicate section with new device identifiers in my xorg.conf file, will this 'just work'? Using different ports on the same video card and separate keyboards, mice, and displays, the result was a desktop which spanned both monitors with both keyboards and mice acting as the same input in the GUI. I will power down and put in the new video card and report on the results soon. Both video cards are nvidia.
after putting in another NVIDIA video card, default behavior (before changing xorg.conf) is that one screen works normally, and both mice and keyboards are connected to it. Changing xorg.conf and the display manager to KDM and following the directions here https://help.ubuntu.com/community/MultiseatX#Ubuntu_10.04_.28Lucid.29 , I have 2 mirrored screens connected to separate video cards, DRI enabled, and 2 mice both connected to the same pointer. Keyboards don't do anything, however, I probably just need to fix a setting in xorg.conf
I would still like to get multiseat functionality, eg. separate screens with separate input devices I have verified that the separate X processes are running (see page above) using 'ps aux | grepX '