From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Deegan Subject: Re: [PATCH] x86/mm: remove the linear mapping of the p2m tables Date: Thu, 13 Sep 2012 15:42:51 +0100 Message-ID: <20120913144251.GC12881@ocelot.phlegethon.org> References: <5052086E020000780009B18D@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5052086E020000780009B18D@nat28.tlf.novell.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: Jan Beulich Cc: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org At 15:23 +0100 on 13 Sep (1347549790), Jan Beulich wrote: > >>> On 13.09.12 at 16:01, Tim Deegan wrote: > > # HG changeset patch > > # User Tim Deegan > > # Date 1347544824 -3600 > > # Node ID a770d1c8448d73ccf2ec36a5322532c2e3c14641 > > # Parent 5691e4cc17da7fe8664a67f1d07c3755c0ca34ed > > x86/mm: remove the linear mapping of the p2m tables. > > > > Mapping the p2m into the monitor tables was an important optimization > > on 32-bit builds, where it avoided mapping and unmapping p2m pages > > during a walk. On 64-bit it makes no difference -- see > > http://old-list-archives.xen.org/archives/html/xen-devel/2010-04/msg00981.html > > Is that also going to remain true when we won't be able to 1:1- > map all of the memory anymore once we break the current 5Tb > barrier? If not, it would probably be worthwhile keeping that > code. Ah, 5TB is a smaller limit than I thought we had. Yes, better leave it alone, so. Though TBH finding some way to use a bit more virtual address space for Xen seems like a good idea anyway, since this won't be the only place we'll want to avoid TLB flushes. Tim.