https://bugs.freedesktop.org/show_bug.cgi?id=41265
--- Comment #43 from Alexander E. Patrakov patrakov@gmail.com 2012-08-16 17:37:28 UTC --- The card is a completely separate card. One can create a very old-fashioned Xinerama-based dual-head setup using this (save as /etc/X11/xorg.conf.d/60-dualhead.conf):
Section "Device" Identifier "radeon" Driver "radeon" BusID "PCI:22:00:0" EndSection
Section "Device" Identifier "intel" Driver "intel" BusID "PCI:00:02:0" EndSection
Section "Screen" Identifier "Screen0" Device "radeon" EndSection
Section "Screen" Identifier "Screen1" Device "intel" EndSection
Section "ServerLayout" Identifier "DualHead" Screen "Screen0" Screen "Screen1" RightOf "Screen0" Option "Xinerama" "On" EndSection
This is, however, deprecated, and I'd also like to know the modern way of doing this :)