From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Maydell Subject: Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it Date: Wed, 3 Oct 2012 21:26:27 +0100 Message-ID: References: <20120930191146.GA20012@amt.cnet> <50694EC1.8060006@siemens.com> <20121001093102.GA14797@amt.cnet> <50696E9E.7030302@siemens.com> <87zk468h3y.fsf@codemonkey.ws> <50699CDC.1010604@redhat.com> <87wqzap9ui.fsf@codemonkey.ws> <5069A9DF.4040606@siemens.com> <87wqza2mg6.fsf@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Anthony Liguori , kvm , Scott Moser , Jan Kiszka , Marcelo Tosatti , Michael Tokarev , qemu-devel , Avi Kivity , Cole Robinson , Paolo Bonzini , =?UTF-8?Q?Andreas_F=C3=A4rber?= , Aurelien Jarno To: Blue Swirl Return-path: Received: from mail-ie0-f174.google.com ([209.85.223.174]:46260 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753370Ab2JCU02 (ORCPT ); Wed, 3 Oct 2012 16:26:28 -0400 Received: by ieak13 with SMTP id k13so18213128iea.19 for ; Wed, 03 Oct 2012 13:26:28 -0700 (PDT) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 3 October 2012 21:01, Blue Swirl wrote: > On Mon, Oct 1, 2012 at 4:20 PM, Anthony Liguori wrote: >> Jan Kiszka writes: >>> + /* The default accelerator depends on the availability of KVM. */ >>> + p = kvm_configured ? "kvm" : "tcg"; >>> } >> Blue/Aurelien, any objections? > > No, maybe a message could be printed that says that the default has > changed, for a few releases. I've lost track of the conversation, are we currently proposing the accelerator default to be "kvm" (as per the original patch you quote here) or "kvm:tcg" ? I'm not entirely sure which I prefer from an ARM perspective For some time to come and for a lot of targets (ie any target CPU except A15), having a default of "kvm" is going to cause existing working commandlines to stop working. [I expect that ARM-host qemu binaries will be built with CONFIG_KVM once ARM KVM support lands, but the same binary will be run on hosts without virtualization extensions.] On the other hand, perhaps there just aren't really very many people who run QEMU on ARM hosts, and so we can ignore them :-) -- PMM From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:57899) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TJVWX-0005v3-RG for qemu-devel@nongnu.org; Wed, 03 Oct 2012 16:26:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TJVWW-0006do-PR for qemu-devel@nongnu.org; Wed, 03 Oct 2012 16:26:29 -0400 Received: from mail-ie0-f173.google.com ([209.85.223.173]:36609) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TJVWW-0006dj-FR for qemu-devel@nongnu.org; Wed, 03 Oct 2012 16:26:28 -0400 Received: by iea17 with SMTP id 17so17124654iea.4 for ; Wed, 03 Oct 2012 13:26:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20120930191146.GA20012@amt.cnet> <50694EC1.8060006@siemens.com> <20121001093102.GA14797@amt.cnet> <50696E9E.7030302@siemens.com> <87zk468h3y.fsf@codemonkey.ws> <50699CDC.1010604@redhat.com> <87wqzap9ui.fsf@codemonkey.ws> <5069A9DF.4040606@siemens.com> <87wqza2mg6.fsf@codemonkey.ws> Date: Wed, 3 Oct 2012 21:26:27 +0100 Message-ID: From: Peter Maydell Content-Type: text/plain; charset=UTF-8 Subject: Re: [Qemu-devel] [PATCH] kvm: Set default accelerator to "kvm" if the host supports it List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Blue Swirl Cc: kvm , Scott Moser , Jan Kiszka , Marcelo Tosatti , Michael Tokarev , qemu-devel , Avi Kivity , Anthony Liguori , Cole Robinson , Paolo Bonzini , =?UTF-8?Q?Andreas_F=C3=A4rber?= , Aurelien Jarno On 3 October 2012 21:01, Blue Swirl wrote: > On Mon, Oct 1, 2012 at 4:20 PM, Anthony Liguori wrote: >> Jan Kiszka writes: >>> + /* The default accelerator depends on the availability of KVM. */ >>> + p = kvm_configured ? "kvm" : "tcg"; >>> } >> Blue/Aurelien, any objections? > > No, maybe a message could be printed that says that the default has > changed, for a few releases. I've lost track of the conversation, are we currently proposing the accelerator default to be "kvm" (as per the original patch you quote here) or "kvm:tcg" ? I'm not entirely sure which I prefer from an ARM perspective For some time to come and for a lot of targets (ie any target CPU except A15), having a default of "kvm" is going to cause existing working commandlines to stop working. [I expect that ARM-host qemu binaries will be built with CONFIG_KVM once ARM KVM support lands, but the same binary will be run on hosts without virtualization extensions.] On the other hand, perhaps there just aren't really very many people who run QEMU on ARM hosts, and so we can ignore them :-) -- PMM