Matrox Multihead on FreeBSD With Xorg 7.3
Updated November 13, 2008, Warren Block (wblock@wonkity.com)


Multihead on FreeBSD with Matrox G450/G550 cards stopped working with 
recent versions of Xorg.  Fortunately, that can be fixed.


IMPORTANT: the xf86-video-mga driver in FreeBSD ports was "backrevved"
to 1.4.7 on January 2, 2008.  That older version supports modelines in
xorg.conf (a feature needed by some), but does not provide multihead or
any xrandr-1.2 features.

If you're already using 1.9.100, you can use portupgrade's "-x" flag to
keep portupgrade from messing with it.  It may be prudent to make a
backup copy of the port directory in case of future changes.

If you weren't paying attention and now have 1.4.7, use
ports-mgmt/portdowngrade to go back to 1.9.100.  For example:

portdowngrade -s freebsdanoncvs@anoncvs.FreeBSD.org:/home/ncvs xf86-video-mga


Software And Hardware Requirements

FreeBSD i386 6.x (tested on 6-STABLE as of June 15, 2008)
FreeBSD i386 7.x (tested on 7.1-PRERELEASE as of November 13, 2008)
Matrox G450 or G550 multihead card (G450 AGP and G550 AGP tested)
FreeBSD ports:
/usr/ports/x11-servers/xorg-server
  versions 1.4_1,1, 1.4_2,1, 1.4_3,1, 1.4_4,1, 1.4_5,1, 1.4_6,1,
           1.4_7,1, 1.4_8,1, 1.4_10,1, 1.4.2,1
/usr/ports/x11-drivers/xf86-video-mga
  versions 1.9.99, 1.9.100

1.  Patch xorg-server:

# cd usr/ports/x11-servers/xorg-server/files
# fetch 'http://www.wonkity.com/~wblock/mgapatch/patch-Pci.c-WB'
# less patch-Pci.c-WB  (read it to see what it does)
# cd /usr/ports/x11-servers/xorg-server/
# make clean deinstall install


2. Update your xorg.conf to use xrandr features:

Example xorg.conf file at

http://www.wonkity.com/~wblock/mgapatch/xorg.conf

It's mostly like an xorg.conf for only one monitor, but defines a large 
Virtual screen in the Screen section.

Each Monitor section has an Option "Position" "x y" that defines the
position of the monitor on the large virtual screen.  The Device section
lets you specify which monitor goes with which output.  The example has
Monitor1 to the left of Monitor0.

The 1.9.100 version of the mga driver doesn't yet support a hardware 
cursor, so that is disabled in the Device section:

Option "HWcursor" "off" 


3. Notes

My AGP versions of the G450 work, and the AGP G550 has been reported to 
work.  Probably the rare PCI version of either card should work, and 
maybe the rare and expensive four-head PCI Matrox cards.  Please let me 
know if you test any of these other cards (or have them sitting in a box 
somewhere and would like to share).

The patch has been reported to allow a single-head G400 to run 
xorg-server, which would not start without it.  The second head on G400 
cards equipped with one isn't yet supported by the mga drivers.

When Xorg on FreeBSD starts to use libpciaccess, this patch will be 
obsolete.  You will have to delete it from the xorg-server files 
directory before building the newer version of the port:

# cd usr/ports/x11-servers/xorg-server/files
# rm patch-Pci.c-WB