Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932189AbXBNJPI (ORCPT ); Wed, 14 Feb 2007 04:15:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932201AbXBNJPI (ORCPT ); Wed, 14 Feb 2007 04:15:08 -0500 Received: from colin.muc.de ([193.149.48.1]:3304 "EHLO mail.muc.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932189AbXBNJPG (ORCPT ); Wed, 14 Feb 2007 04:15:06 -0500 Date: 14 Feb 2007 10:15:04 +0100 Date: Wed, 14 Feb 2007 10:15:04 +0100 From: Andi Kleen To: Jan Beulich Cc: Jeremy Fitzhardinge , virtualization@lists.osdl.org, xen-devel@lists.xensource.com, Andrew Morton , Chris Wright , linux-kernel@vger.kernel.org, Dan Hecht Subject: Re: [Xen-devel] Re: [patch 05/21] Xen-paravirt: paravirt_ops: allocate a fixmap slot Message-ID: <20070214091504.GA68112@muc.de> References: <20070213221729.772002682@goop.org> <20070213221829.845132535@goop.org> <45D2649D.4080508@vmware.com> <45D26797.5090600@goop.org> <45D2D856.76E4.0078.0@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45D2D856.76E4.0078.0@novell.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 26 On Wed, Feb 14, 2007 at 08:37:26AM +0000, Jan Beulich wrote: > >>> Jeremy Fitzhardinge 14.02.07 02:36 >>> > >Dan Hecht wrote: > >> Why doesn't Xen allocate the shared_info page from the pseudo-physical > >> space? Doesn't it already have to steal pages from the > >> pseudo-physical space for e.g. initial page tables, console, etc? Why > >> not do the same for shared_info, and then you don't need a reserve the > >> fixmap slot. > > > >Unlike the pagetable pages or the console page, the shared info page > >doesn't have a pseudo-physical address, so in order to map it we need to > >directly construct a pte containing the mfn for that page. Inserting > >this mapping into the fixmap space seems like the easiest way to do > >this. It's not like a fixmap slot costs anything. > > Otoh there are many fixmap slots not used under Xen, perhaps it would > be possible to use one of those... One slot certainly doesn't cost a lot, I don't have a problem with reserving one page for this. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/