> Error: (2, 'Invalid kernel', 'xc_dom_compat_check: guest type > xen-3.0-x86_32 not supported by xen kernel, sorry\n')
Probable cause is that your Xen is configured with PAE enabled, which means it won't boot non-PAE kernels. Plan 9 Xen kernel currently doesn't support PAE. Look for "xen3 and pae problems" in comp.os.plan9 for discussion on this topic.
