should list all the pci devices on your machine. You may have to install the pciutils package if it isn't already installed.
I might suggest
the Xinerama howto also. After that, I'm afraid I won't be of much help as I've never set up a multi-head system.
EDIT: After paging through the howto, I realize now that you are probably already using it. In order to run the
command, the X server can't be running. You will have to kill the running X server.
As root:
Code:
# /etc/init.d/{xdm,gdm,kdm} stop
You may have to choose and only input the login manager you are actually using at the end of that line and remove the curly braces. I didn't actually try the above command as it is. Let me know if I've totally confused you.
Anyhoo, once you've dropped to the command line, login and try your -scan command. Otherwise, like I said, the lspci command works too.