Xorg/XFree86 Dualhead Status

Chip	Open/Binary	Dualhead Support*	MergedFB Support**	Documentation available	Video Overlays	HW cursors	Notes
Radeon (rv100-r4xx)	open	yes	yes	ATI makes databooks available to developers	1	2	Supported in Xorg
Rage 128 (M3, M4)	open	yes	soon	ATI makes databooks available to developers	1	2	Available in Xorg
Mach 64 (M1/Mobility)				ATI makes databooks available to developers	1	2	I'd be willing to write a driver pending time and access to a M1 based laptop
Savage (savage MX/IX, supersavage)	open	yes	yes	Some developers have access to the databooks. S3/VIA has been very helpful.	2	2	See my duoview page; Regular dualhead support available in Xorg. MergedFB support will follow at some point.
Virge (virge mx/mx+)				Some developers have access to the databooks	1	1	works similarly to savage
Via (CLE266, KM400, KN400, K8M800, K8N800)	open	yes	a similar feature: "drixinerama" (untested)	S3/VIA provides source code	1?	?	Supported in Xorg; See the unichrome project
SiS (300, 315, 330 series)	open	yes	yes	Possibly. SiS/XGI may be opening up.	1 or 2 (depends on chip)	2	Supported in Xorg; See Thomas' site
XGI	open	yes	yes	Possibly. XGI may be opening up.	1 or 2 (depends on chip)	2	Supported in Xorg; See Thomas' site
Matrox (G400, G450, G550)	open/binary	yes (G400 requires binary HAL module)	yes (requires binary HAL module)	yes	1	1	Supported in Xorg; pseudo-xinerama patch; G400 requires HAL module for dualhead support
Silicon Motion (712, 722, 731, 501)	open	no	sort of (chip specific "dualhead" option)	Full databooks (2D, 3D, dualhead, video, etc.) available on their website	2/4	1/2	Lynx chips supported in Xorg. 501 support here (new driver) in progress.
Intel (i830-i9xx)	open	yes	yes	no	1	2	Supported in Xorg
Chips (69030)	open	yes	no	yes, available here	1?	?	Supported in Xorg
Trident				Some developers have access to the databooks. The VIA PLE133 databook has documentation for trident chips.	?	?
3DLabs				?	?	?
Neomagic				no	?	?

* Dualhead support refers to standard "xinerama" style multi-head. In this case there are two instances of the driver sharing access to the hardware, each with its own framebuffer and handling one output.

** MergedFB dualhead is a special kind of dualhead where both crtcs share the same framebuffer (hence merged framebuffer); because of this MergedFB tends to be faster (no copying data from one FB to another, no sharing of the drawing engine, etc.) and the DRI works on both heads. Dualhead with 3D acceleration!

If you have any questions about this page or feel you might have something to contribute (such as hardware or databooks), send me email at agd5f (at) yahoo (d.o.t.) com.