From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=40973 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OQKd3-0003Bz-Qw for qemu-devel@nongnu.org; Sun, 20 Jun 2010 09:32:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OQKd2-0006Yd-I8 for qemu-devel@nongnu.org; Sun, 20 Jun 2010 09:32:05 -0400 Received: from mail2.shareable.org ([80.68.89.115]:52026) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OQKd2-0006Xf-Dw for qemu-devel@nongnu.org; Sun, 20 Jun 2010 09:32:04 -0400 Date: Sun, 20 Jun 2010 14:31:56 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: [Bug 596106] Re: kvm to emulate 64 bit cpu on 32 bit host Message-ID: <20100620133156.GB15818@shareable.org> References: <20100618221506.20805.22930.malonedeb@wampee.canonical.com> <20100619130104.20805.94396.malone@wampee.canonical.com> <4C1DE713.6080504@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C1DE713.6080504@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Bug 596106 <596106@bugs.launchpad.net>, qemu-devel@nongnu.org Paolo Bonzini wrote: > On 06/19/2010 03:01 PM, Natalia Portillo wrote: > >VMWare is able to do it, we should be able. > > They do it like TCG does it, not like KVM. I heard rumours VMWare use KVM-style chip virtualisation when running a 64-bit guest on a 32-bit host kernel on 64-bit hardware. If true, that makes particular sense for Windows host users, who can't just drop in a 64-bit host kernel without breaking their userspace thoroughly. (If it was that easy, 64-bit Windows wouldn't use a surruptitious VM to run 32-bit apps :-). It seems like a good way for Windows users to run a single 64-bit app on an otherwise 32-bit system that's working fine. On Linux hosts I would expect you can drop in a 64-bit kernel, while continuing to run a 32-bit userspace. But I don't know if (a) that's entirely true, and (b) if distro packaging blocks that sort of thing from being easy. Unfortunately even that doesn't help people who just want to run a 64-bit VM as an ordinary user and aren't permitted to change their Linux host kernel, e.g. a shared system, or some rented servers. -- Jamie