From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [Xen-devel] [PATCH 0/2] xen: Switch to virtual mapped linear p2m list Date: Tue, 28 Oct 2014 12:46:36 +0000 Message-ID: <544F902C.8040502@citrix.com> References: <1414421551-31555-1-git-send-email-jgross@suse.com> <544E61DD.8050305@citrix.com> <544F22E4.9040706@suse.com> <1414489898.23883.25.camel@citrix.com> <544F83C1.3010402@citrix.com> <544F8713.9040803@suse.com> <544F8E89.6070006@citrix.com> <544F8F3A.3030505@citrix.com> <544F8FBB.2010709@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <544F8FBB.2010709@citrix.com> Sender: linux-kernel-owner@vger.kernel.org To: David Vrabel , Juergen Gross , Ian Campbell Cc: boris.ostrovsky@oracle.com, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org List-Id: xen-devel@lists.xenproject.org On 28/10/14 12:44, David Vrabel wrote: > On 28/10/14 12:42, Andrew Cooper wrote: >> On 28/10/14 12:39, David Vrabel wrote: >>> On 28/10/14 12:07, Juergen Gross wrote: >>>> Okay, back to the original question: is the (up to) 64 MB virtual >>>> mapping of the p2m list on 32-bit pv domains a problem or not? >>> I think up-to 64 MiB of vmalloc area is fine. The vmalloc space can be >>> increased with a command line option in the unlikely event that there >>> are domUs that would be affected. >>> >>>> If yes, the virtual mapped linear p2m list could still be used on >>>> 64 bit domains, paving the way for support of more than 512 GB of >>>> domain memory. OTOH having to keep the p2m tree coding alive isn't >>>> my favorite solution... >>> Having to keep both the tree and linear p2m code would be awful. Let's >>> not do this! >>> >>> David >> How is the toolstack expected to find and mutate this p2m on migrate? >> The toolstack does not use guest pagetables. > The p2m code maintains two trees. One for use by the guest and one for > use by the toolstack. This series replaces the first tree with the > linear array (at least that's how I understand it -- I've not reviewed > the series in detail yet). Ah - fine (if that is how it works). ~Andrew