From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57893) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uzppi-0000v8-Ku for qemu-devel@nongnu.org; Thu, 18 Jul 2013 11:09:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uzpph-0006Zi-HH for qemu-devel@nongnu.org; Thu, 18 Jul 2013 11:09:30 -0400 Received: from [2001:41d0:8:2b42::1] (port=45818 helo=ns232118.ovh.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uzpph-0006Zd-Au for qemu-devel@nongnu.org; Thu, 18 Jul 2013 11:09:29 -0400 Message-ID: <51E80525.6090607@greensocs.com> Date: Thu, 18 Jul 2013 17:09:25 +0200 From: Frederic Konrad MIME-Version: 1.0 References: <1374159757-16383-1-git-send-email-fred.konrad@greensocs.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC 0/3] Determinitic behaviour with icount. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: pbonzini@redhat.com, mark.burton@greensocs.com, qemu-devel@nongnu.org On 18/07/2013 17:06, Peter Maydell wrote: > On 18 July 2013 16:02, wrote: >> As I said in the last email, we have issues with determinism with icount. >> We are wondering if determinism is really ensured with icount? > My opinion is that it *should* be deterministic but it would > be unsurprising if the determinism had got broken along the way. Yes, the documentation say that this command can give deterministic results that's why we asked. > >> Both icount and reverse execution need an instruction counter. icount use a >> count-down mechanism but reverse execution need a continuous counter. For now >> we have build a separate counter and we think that these two counters can be >> merged. However we would like feedback about this before modifying this. > I definitely think that there should only be one counter, not two. > > thanks > -- PMM