[Pkg-xen-devel] Bug#520641: Bug#520641: Cannot create HVM domain

[Pasi Kärkkäinen]

On Fri, Jul 10, 2009 at 10:39:42AM +0100, Richard Kettlewell wrote:
> Romain Francoise wrote:
> >This happens when there's not enough free memory to compensate the
> >memory overhead of domain creation, xend balloons down dom0 by 2MB
> >to work around this, but sometimes it's not enough.
> >
> >Freeing more memory manually, or disabling ballooning of dom0
> >altogether (a good idea in any case) fixes it.
> 
> Sorry, freeing more memory where and how?  It's a 4GB machine with 960MB 
> allocated to the current (PV) guests.
> 
> I have only the vaguest idea of what "ballooning" means (something to do 
> with controlling the memory available to domains?), and no idea why it 
> might be a bad idea or how to turn it off.
> 
> If any of this is documented anywhere then I must have missed some 
> important piece of documentation!
> 

First of all, have you limited the amount of memory dom0 has? 

in grub.conf, add "dom0_mem=" parameter for xen.gz. This way dom0 only has
the specified amount of memory (512 MB for example), and the rest is
available for other domains.. then you don't need to balloon the memory
at all when creating more domains/guests.

"xm info" should display the rest of the memory as free after you specify
dom0_mem parameter for xen hypervisor.

-- Pasi