From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36786) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T6fYM-00033j-PU for qemu-devel@nongnu.org; Wed, 29 Aug 2012 06:31:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T6fYH-0005kq-2r for qemu-devel@nongnu.org; Wed, 29 Aug 2012 06:31:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1638) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T6fYG-0005kk-N8 for qemu-devel@nongnu.org; Wed, 29 Aug 2012 06:31:12 -0400 Date: Wed, 29 Aug 2012 13:32:26 +0300 From: "Michael S. Tsirkin" Message-ID: <20120829103226.GE5225@redhat.com> References: <20120828191338.GE6223@otherpad.lan.raisama.net> <20120828213527.GB5817@redhat.com> <20120828220242.GW2886@otherpad.lan.raisama.net> <20120828222113.GA5970@redhat.com> <20120829095903.GB32031@amt.cnet> <20120829100334.GB561@amt.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120829100334.GB561@amt.cnet> Subject: Re: [Qemu-devel] [PATCHv4 3/4] cpuid: disable pv eoi for 1.1 and older compat types List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcelo Tosatti Cc: gleb@redhat.com, kvm@vger.kernel.org, qemu-devel@nongnu.org, Blue Swirl , Jan Kiszka , avi@redhat.com, Anthony Liguori , Eduardo Habkost On Wed, Aug 29, 2012 at 07:03:34AM -0300, Marcelo Tosatti wrote: > On Wed, Aug 29, 2012 at 06:59:03AM -0300, Marcelo Tosatti wrote: > > > I don't understand. What is the problem with the proposal? > > > What will not work with our protocol? > > > Can you give an example please? > > > > > > > > > > > Too late for 1.2? > > > > > > > > Absolutely (in my opinion). > > > > My concern here is that you are introducing infrastructure by using > > _one example_, claiming it to solve a general problem, without the > > appropriate amount of energy spent in this solution. > > > > Using old machines is supposed to be supported on older guests. > > > > Michael, not migrating the PVEOI MSR actually crashes the guest? > > Which is irrelevant since it won't be able to migrate to an older > qemu. > With this patch, -M pc-1.1 migrates fine to an older qemu and no crash. Without, PV EOI bit in CPUID is set on source so we have a problem. -- MST