Running X Windows with OpenSSI

* Running X on more than one node:

First edit /etc/inittab to add a U to the runlevel for prefdm. This 
tells the SSI-enhanced init to start prefdm on every node:

 # Run xdm in runlevel 5
-x:5:respawn:/etc/X11/prefdm -nodaemon
+x:5U:respawn:/etc/X11/prefdm -nodaemon

Each instance of X creates unix domain sockets in /tmp. To prevent
namespace collisions between them, each node must have its own
/tmp. So we must replace /tmp with a context-dependent symlink
(CDSL). Assuming bash and that node 1 is your initnode:

# mklocalfile /tmp
# rm -rf /cluster/node[1-9]*/tmp/.font-unix
# mkglobalfile /tmp/.font-unix
# rm /cluster/node1/tmp/.font-unix
# mv /cluster/tmp/.font-unix /cluster/node1/tmp
# ln -s /cluster/node1/tmp/.font-unix /cluster/tmp/.
# mklocalfile /var/gdm
# for i in /cluster/node*/var/log ; do mkdir -p $i/gdm ; done

Now each node effectively has its own /tmp and all nodes will use the
X fontserver on node 1 (replace node1 in the above commands if you have 
a different initnode).

It's also a good idea to apply the following patch to /etc/console.perms:

--- /etc/security/console.perms.dist    2003-02-10 21:43:43.000000000
+0100
+++ /etc/security/console.perms 2003-11-10 15:02:01.000000000 +0100
@@ -15,7 +15,7 @@
 # man 5 console.perms
 
 # file classes -- these are regular expressions
-<console>=tty[0-9][0-9]* vc/[0-9][0-9]* :[0-9]\.[0-9] :[0-9]
+<console>=tty[0-9][0-9]* ([0-9]+/)?vc/[0-9][0-9]* :[0-9]\.[0-9] :[0-9]
 <xconsole>=:[0-9]\.[0-9] :[0-9]
 
 # device classes -- these are shell-style globs