xm mem-max and mem-set

["Ky Srinivasan" <ksrinivasan@novell.com>]

It appears that these commands (and code backing these commands) do no
sanity checking and could potentially get the system to crash if the
values picked are not appropriate. For instance one can set the mem-max
value to a value that appears reasonable and basically render the
machine unusable. Consider the case where max value being set is less
than what is currently allocated to the domain. All subsequent
allocations will fail and these failures are considered fatal in Linux
(look at hypervisor.c). Once the domain is up, does it even make sense
to lower the max_mem parameter without risking crashing the system?
Minimally, we should ensure that the mem_max value is at least equal to
what the current domain allocation is. I have a trivial patch to xen
that implements this logic. This patch fixes a bug we have in our
bugzilla against SLES10. Would there be interest in such a patch. 

Regards,

K. Y