RE: [Xen-devel] How to determine memory size in HVM

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> On 10/06/2009 12:39, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
wrote:
> 
> >> Yes, that's the framebuffer. It is variable size, in principle,
> > though. I'm
> >> not sure you can do better than read XENMEM_current_reservation and
> >> memory/target at driver startup time, and keep the delta between
them
> >> constant.
> >
> > There is a XENMEM_maximum_reservation, which I think makes it 8MB
> > exactly instead of 8060KB (7.xxxMB). Would I be better off using
that as
> > a comparison?
> 
> I don't think you should depend on that.

Ok. thanks.

> 
> Perhaps just having XENMEM_current_reservation track memory/target
would be
> fine. I'm not sure if it will make e.g. The memory values returned by
'xm
> list' incorrect.
> 
> We might have to provide more info to you via xenstore to do the 100%
right
> thing here.

Well I think the main problem is that if you shrink the DomU and then
reboot, you can't ever grow it again as Windows thinks it booted with
less memory. While there is the ability to add memory to a running
Windows machine, it is the 'hot add memory' (eg plugging in a memory
stick) and involves ACPI and only works under the Windows Server
Enterprise editions (which might still be useful, but probably not worth
the headaches involved in the ACPI work). I think the other issues are
minor in comparison to this problem.

Thanks

James

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel