From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:38524) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TDeov-0000f9-RR for qemu-devel@nongnu.org; Mon, 17 Sep 2012 13:09:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TDeoq-0005D7-Vd for qemu-devel@nongnu.org; Mon, 17 Sep 2012 13:09:17 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:44315) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TDeoq-0005Cw-Py for qemu-devel@nongnu.org; Mon, 17 Sep 2012 13:09:12 -0400 Received: by wibhm2 with SMTP id hm2so2010272wib.10 for ; Mon, 17 Sep 2012 10:09:12 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <50575934.5070304@redhat.com> Date: Mon, 17 Sep 2012 19:09:08 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1347897649-23236-1-git-send-email-pbonzini@redhat.com> <1347897649-23236-2-git-send-email-pbonzini@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH 01/10] configure: factor out list of supported Xen/KVM targets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: qemu-devel@nongnu.org, Stefano Stabellini Il 17/09/2012 19:02, Peter Maydell ha scritto: > If Xen requires 64 bit physaddrs it should probably just be asserting > this here, not randomly changing target_phys_bits. In fact all the > supported Xen target archs already have 64 bit physaddrs, so it's > harmless. But if there ever were a target Xen arch which didn't support > 64 bit phys addrs then the right approach would be to convert it to > do so regardless of whether we were using Xen or not. No, Xen does not require 64-bit physaddrs, but it supports them even if you build it for 32-bit. Memory is accessed through a "hole" (the mapcache) provided by the hypervisor, so that a 32-bit QEMU address space is enough to run 64-bit guests. At least that's my understanding. Paolo