Re: [PATCH] Disallow setting maxmem to higher value than total physical memory size

[Jeremy Fitzhardinge <jeremy@goop.org>]

 On 09/01/2010 05:44 AM, Ian Campbell wrote:
> On Wed, 2010-09-01 at 13:31 +0100, Michal Novotny wrote:
>> Hi,
>> this is the patch to disallow changing the maxmem value to higher value 
>> than total physical memory size since without this patch I was able to 
>> set dom0 maxmem to higher (invalid) value which is not correct.
> I think it is allowable for a domU though. Consider the scenario where
> you have two hosts, one of which has more physical RAM than the other.
> You may which to boot a domain on the smaller host, (i.e. booting
> ballooned with a current_pages suitable for the small host) and then
> migrate it to the large machine where you then want to be able to
> balloon to a value larger than was even possible on the previous
> machine.

But max-mem can change between hosts; on the small host it needn't have
a maxmem larger than the host's memory.  (The domain itself may have a
larger notion of maxmem internally, but that's separate.)

    J