Comment 2 for bug 816180

Although the XGI device is detected by xorg, no driver is loaded because the SiS driver has now replaced the XGI driver.
This can be solved by directing the "xgi" identifier to the "sis" driver in (lucid) /usr/lib/X11/xorg.conf.d/09-xgi.conf:

Section "Device"
        Identifier "xgi"
        Driver "sis"
        Endsection

The same fix works in Maverick, but the path is: /usr/share/X11/xorg.conf.d/09-xgi.conf

Another, related, bug is that the "sis" driver does not load the "sisfb" module: This can be worked around by adding the "sisfb" module to /etc/modules

HTH,

  Tony.