2.6.16 nor FC5 -xenU kernel will start under 3.0-testing

[Matt Ayres <matta@tektonic.net>]

I tried building a 2.6.16 kernel from -unstable and also the -xenU 
kernel provided by FC5 and both will not run under 3.0-testing 
(changeset 8761:484a14acfc26).

The 2.6.16 kernel will start and die with nothing of value in xend.log 
or xend-debug.log.  If I run "xm create name -c" it will say it can't 
open "/dev/pts/XX" and that is all the information I can provide.

If I try to boot the 2.6.15 FC5 -xenU kernel (and accompanying initrd 
using the ramdisk config file option) it simply get "Invalid argument" 
when executing xm create.

Is not the point of a 3.0 branch that kernels compiled for 3.0.x will 
run under any version or is there new coded added to both of these 
kernels that prevent it from running under my older version of Xen?  I 
could see a kernel developed for Xen 3.1 not working with 3.0.x, but my 
impression was 3.0.x were all meant to be compatible with each other 
(forward and backward).

If this is not meant to work let me know, otherwise I will open up a bug .

Thank you,
Matt Ayres