From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Performance of 32-bit PAE vs. 64-bit kernel regarding 16-bit instruction Date: Tue, 05 Apr 2011 11:18:29 +0300 Message-ID: <4D9AD055.9050500@redhat.com> References: <923f45e136b34909ef809036d3cbe83b@127.0.0.1> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Andreas Bollhalder Return-path: Received: from mx1.redhat.com ([209.132.183.28]:18543 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753053Ab1DEISf (ORCPT ); Tue, 5 Apr 2011 04:18:35 -0400 In-Reply-To: <923f45e136b34909ef809036d3cbe83b@127.0.0.1> Sender: kvm-owner@vger.kernel.org List-ID: On 04/04/2011 04:40 PM, Andreas Bollhalder wrote: > Hello > > Does anyone have some advises regarding running a 16-bit executable in a > virtualized 32-bit OS under KVM ? Would it be better to run a 32-bit linux > kernel with PAE or a 64-bit kernel on the host ? It doesn't matter. 64-bit is slightly preferable. > I imagine that KVM has to emulate all 16-bit instruction of a VM if > running under a 64-bit host kernel. If using a 32-bit kernel, KVM could be > able to use the vm86 mode for 16-bit instructions. No, in both cases kvm uses whatever mode the guest asks for. > I know that PAE should be obsolete. But in my special case, I would use a > host with 16 GB of RAM running different 32-bit VMs executing 16-bit > binaries. > With 16GB of RAM 64-bit is the way to go. -- error compiling committee.c: too many arguments to function