From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751778Ab2IGP7V (ORCPT ); Fri, 7 Sep 2012 11:59:21 -0400 Received: from acsinet15.oracle.com ([141.146.126.227]:33452 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751128Ab2IGP7T (ORCPT ); Fri, 7 Sep 2012 11:59:19 -0400 Date: Fri, 7 Sep 2012 11:48:27 -0400 From: Konrad Rzeszutek Wilk To: Jan Beulich Cc: Stefan Bader , Matt Wilson , "Justin M. Forbes" , xen-devel@lists.xen.org, Linux Kernel Mailing List Subject: Re: [Xen-devel] [PATCH/RFC] Fix xsave bug on older Xen hypervisors Message-ID: <20120907154827.GA6059@phenom.dumpdata.com> References: <1347018043-21252-1-git-send-email-stefan.bader@canonical.com> <504A05B00200007800099C7B@nat28.tlf.novell.com> <5049F4E9.9050306@canonical.com> <504A1A950200007800099D4C@nat28.tlf.novell.com> <20120907142251.GA20096@linuxtx.org> <504A32800200007800099E40@nat28.tlf.novell.com> <504A172B.5020005@canonical.com> <504A347B0200007800099E92@nat28.tlf.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <504A347B0200007800099E92@nat28.tlf.novell.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 07, 2012 at 04:52:59PM +0100, Jan Beulich wrote: > >>> On 07.09.12 at 17:47, Stefan Bader wrote: > > On 07.09.2012 17:44, Jan Beulich wrote: > >> All of this still doesn't provide evidence that a plain upstream > >> kernel is actually having any problems in the first place. Further, > >> if you say EC2 has a crippled hypervisor patch - is that patch > >> available for looking at somewhere? > > > > It was not a hypervisor patch. It was one for the guest. This was the hack: > > So then why do you want to patch the upstream kernel? It won't > make that hack go away, nor will it help any existing kernels. It will make both distro ditch that patch - and instead they can use this. [As we can ask them to ditch their crippled patch and they can rest safely knowing that the upstream kernel has a quirk workaround for what they had been hitting for ages] Also with this patch any upstream kernel that runs on Amazon EC2 will not run in-to the issue that Fedora and Canonical ran with an virgin kernel when they were deploying it first time. The Amazon EC2 guidelines have it spelled out somewhere that one can't depend on certain things - even if they are detected. This was one of them, and MWAIT I believe was the other. It won't fix existing kernels - that is true but that is not what the purpose of this patch is. > > Jan