From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Ostrovsky Subject: Re: [PATCHv1] xen/balloon: disable memory hotplug in PV guests Date: Mon, 09 Mar 2015 11:25:07 -0400 Message-ID: <54FDBB53.7070108@oracle.com> References: <1425910200-17541-1-git-send-email-david.vrabel@citrix.com> <54FDB7B8.7000305@oracle.com> <54FDB8A4.9020904@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YUzZl-00008t-00 for xen-devel@lists.xenproject.org; Mon, 09 Mar 2015 15:26:37 +0000 In-Reply-To: <54FDB8A4.9020904@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: David Vrabel , xen-devel@lists.xenproject.org Cc: Daniel Kiper List-Id: xen-devel@lists.xenproject.org On 03/09/2015 11:13 AM, David Vrabel wrote: > On 09/03/15 15:09, Boris Ostrovsky wrote: >> On 03/09/2015 10:10 AM, David Vrabel wrote: >>> Memory hotplug doesn't work with PV guests because: >>> >>> a) The p2m cannot be expanded to cover the new sections. >>> >>> b) add_memory() builds page tables for the new sections which means >>> the new pages must have valid p2m entries (or a BUG occurs). >> Is this due to recent p2m rework? > (a) is but (b) has always meant memory hotplug on PV was broken. I can see why (b) should probably have prevented it from working but I tried this on 4.4/3.17 and that seemed to work (it indeed does not function well on newer bits). -boris