From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH] Disallow setting maxmem to higher value than total physical memory size Date: Wed, 01 Sep 2010 09:53:55 -0700 Message-ID: <4C7E8523.2080108@goop.org> References: <4C7E47B2.9010805@redhat.com> <1283345049.12544.9494.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1283345049.12544.9494.camel@zakaz.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Ian Campbell Cc: Michal Novotny , "'xen-devel@lists.xensource.com'" List-Id: xen-devel@lists.xenproject.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