updating to xfree 4 with mach64

[Dave Love <d.love@dl.ac.uk>]

What does one have to do to get a working X server on an Ultra 5
(Mach64 card) after a dist-upgrade from stable to testing?  [Sorry if
this has been covered before, as I'd have expected, but I haven't
spotted it.]

I've ended up with xserver-common-4.0.2-7, xserver-xfree86-4.0.2-7 and
xserver-mach64-3.3.6-11potato; apparently nothing is configured
properly and it's not clear how to arrange that.  On booting, xdm eats
CPU and does nothing useful.  startx can't find /etc/X11/X.  Running
xf86cfg crashes the box.

It's not clear to me whether this is a generic issue or SPARC
specific.