From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MDdZn-0001Jp-Hg for qemu-devel@nongnu.org; Mon, 08 Jun 2009 08:03:43 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MDdZi-0001I3-TA for qemu-devel@nongnu.org; Mon, 08 Jun 2009 08:03:43 -0400 Received: from [199.232.76.173] (port=35644 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MDdZi-0001Hw-Mb for qemu-devel@nongnu.org; Mon, 08 Jun 2009 08:03:38 -0400 Received: from mx2.redhat.com ([66.187.237.31]:32931) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MDdZh-00041A-Jb for qemu-devel@nongnu.org; Mon, 08 Jun 2009 08:03:38 -0400 Message-ID: <4A2CFE07.90700@redhat.com> Date: Mon, 08 Jun 2009 15:03:19 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] POLL: Why do you use kqemu? References: <4A26F1E3.1040509@codemonkey.ws> <4A27FC69.9070501@mayc.ru> <20090605201415.GA22847@csclub.uwaterloo.ca> <20090608001312.GE15426@shareable.org> <4A2CA8C2.2080004@redhat.com> <20090608115755.GD25684@shareable.org> In-Reply-To: <20090608115755.GD25684@shareable.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jamie Lokier Cc: Lennart Sorensen , "qemu-devel@nongnu.org" , Anton D Kachalov Jamie Lokier wrote: >>> Plus kvm's not suitable for some guests. I'm thinking old Windows >>> guests with 16-bit kernel code here. >>> >>> >> kvm on amd will run these perfectly. >> > > So the "Guest Support Status" prominently on the front page of > linux-kvm.org is wrong for current versions? It specifically mentions > AMD hosts. > > (I notice AMD KVM != Intel KVM hasn't factored into this discussion yet...) > > Guest KVM tested Host CPU/bits Result > ---------------------------------------------------------------- > Windows 98SE kvm-63 Intel 32 Fails > Windows 98SE kvm-80, 2.6.27.7 AMD 64 no way > Windows 95 kvm-44, 2.6.23-rc8 AMD 64, 32 no way > Well, maybe there's some other bug in there. But kvm-amd 16 bit support is as good as the native cpu's. kvm-intel with the new 'unrestricted guest' should be the same. >>> It has come up before that kvm will eventually support 16-bit code >>> better, although I got the impression that it would never support full >>> 16-bit virtualisation accurately, so e.g. Windows 95 will not run on >>> it, nor some other partially 16-bit OSes. Possibly not even very old >>> versions of Linux, I'm not sure. >>> >>> Don't ask me _why_ I want to run them. :-) >>> >>> Just a data point that it's not just about the host hardware, and as >>> far as I know kqemu can accelerate them. >>> >>> >> It falls back to qemu for 16-bit code. >> > > I was under the impression it was planned to remove TCG support when > using KVM. If not, fine, it's ok for 16-bit code to run in TCG and > probably better than vm86 or the in-kernel interpreter. > vm86 doesn't work on x86_64. kvm will run most 16-bit code natively, just have to complete task switch support and fix any bugs. -- error compiling committee.c: too many arguments to function