Along with the blktap hardcoding of a major number. It has come to my 
attention that evtchn also hardcodes a minor number.  Not so bad, but 
can later cause conflicts.  evtchn uses the misc device to get its major 
number.

This patch makes evtchn use a dynamic minor number instead.  It also 
updates the code in tools to create the device node if udev fails.  The 
tools now read the sysfs system to find the minor number needed.


One thing that is missing though, in this patch, is the update to 
./debugger/pdb/evtchn.ml, which still has the hard coded 201 as the 
minor.  This calls evtchn_open which is a C function that creates the 
node if it doesn't already exist.  I don't know much about Modula-2 but 
the major and minor probably don't need to be passed in, and the C code 
can do the same thing as the tools do now.  But I'll let others decide 
on that.

-- Steve

Signed-off-by: Steven Rostedt <srostedt@redhat.com>