From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MwIfV-0000u9-Ex for qemu-devel@nongnu.org; Fri, 09 Oct 2009 12:50:13 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MwIfQ-0000tV-Vp for qemu-devel@nongnu.org; Fri, 09 Oct 2009 12:50:13 -0400 Received: from [199.232.76.173] (port=36720 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MwIfQ-0000tS-SB for qemu-devel@nongnu.org; Fri, 09 Oct 2009 12:50:08 -0400 Received: from mail2.shareable.org ([80.68.89.115]:42876) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MwIfQ-0008BQ-B4 for qemu-devel@nongnu.org; Fri, 09 Oct 2009 12:50:08 -0400 Date: Fri, 9 Oct 2009 17:49:55 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: [PATCH v2 3/9] provide in-kernel ioapic Message-ID: <20091009164955.GC7393@shareable.org> References: <1254953315-5761-1-git-send-email-glommer@redhat.com> <1254953315-5761-2-git-send-email-glommer@redhat.com> <1254953315-5761-3-git-send-email-glommer@redhat.com> <1254953315-5761-4-git-send-email-glommer@redhat.com> <4ACDEDEC.60706@us.ibm.com> <4ACDEF03.6010406@redhat.com> <20091008160726.GD29691@shareable.org> <4ACE10B5.3080509@redhat.com> <20091008162248.GK16702@redhat.com> <20091009143225.GV8092@mothafucka.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091009143225.GV8092@mothafucka.localdomain> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Glauber Costa Cc: kvm-devel , Anthony Liguori , Avi Kivity , Gleb Natapov , qemu-devel@nongnu.org Glauber Costa wrote: > On Thu, Oct 08, 2009 at 06:22:48PM +0200, Gleb Natapov wrote: > > On Thu, Oct 08, 2009 at 06:17:57PM +0200, Avi Kivity wrote: > > > On 10/08/2009 06:07 PM, Jamie Lokier wrote: > > > >Haven't we already confirmed that it *isn't* just an ioapic accelerator > > > >because you can't migrate between in-kernel iopic and qemu's ioapic? > > > > > > We haven't confirmed it. Both implement the same spec, and if you > > > can't migrate between them, one of them has a bug (for example, qemu > > > ioapic doesn't implement polarity - but it's still just a bug). > > > > > Are you saying that HW spec (that only describes software visible behavior) > > completely defines implementation? No other internal state is needed > > that may be done differently by different implementations? > Most specifications leaves a lot as implementation specific. > > It's not hard to imagine a case in which both devices will follow > the spec correctly, (no bugs involved), and yet differ in the > implementation. Avi's not saying the implementations won't differ. I believe he's saying that implementation-specific states don't need to be saved if they have no effect on guest visible behaviour. -- Jamie