From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:54809) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tkc2R-0001Sy-Az for qemu-devel@nongnu.org; Mon, 17 Dec 2012 09:51:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tkc2M-0000Ud-Ll for qemu-devel@nongnu.org; Mon, 17 Dec 2012 09:51:27 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60024) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tkc2M-0000UY-CV for qemu-devel@nongnu.org; Mon, 17 Dec 2012 09:51:22 -0500 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id qBHEpLjt029267 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 17 Dec 2012 09:51:21 -0500 Message-ID: <50CF3167.7080707@redhat.com> Date: Mon, 17 Dec 2012 15:51:19 +0100 From: Gerd Hoffmann MIME-Version: 1.0 References: <1355492147-5023-1-git-send-email-hdegoede@redhat.com> <1355492147-5023-10-git-send-email-hdegoede@redhat.com> <50CF1B33.7060708@redhat.com> <50CF2AFB.2050705@redhat.com> <50CF2EB3.9020501@redhat.com> <50CF308C.70204@redhat.com> In-Reply-To: <50CF308C.70204@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 09/26] ehci: Use uframe precision for interrupt threshold checking List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hans de Goede Cc: qemu-devel@nongnu.org On 12/17/12 15:47, Hans de Goede wrote: > Hi, > > On 12/17/2012 03:39 PM, Gerd Hoffmann wrote: >> On 12/17/12 15:23, Hans de Goede wrote: >>> Hi, >>> >>> On 12/17/2012 02:16 PM, Gerd Hoffmann wrote: >>>> On 12/14/12 14:35, Hans de Goede wrote: >>>>> Note that a shadow variable is used instead of changing frindex to >>>>> uframe accuracy because we must send a frindex which is a multiple >>>>> of 8 >>>>> during migration for migration compatibility, and rounding it down to >>>>> a multiple of 8 pre-migration, can lead to frindex going backwards >>>>> from >>>>> the guest pov. >>>> >>>> Jumping forward instead? >>> >>> You mean rounding the send frindex up pre-migration, I didn't really >>> consider >>> that as it will cause us skipping processing an entry in the periodic >>> frame >>> list. I guess doing that on migration isn't too bad. OTOH giving the >>> guest >>> only frame accuracy like we've been doing till now also works fine... >>> >>> Your choice :) >> >> I'm looking for a way to avoid the shadow variable, but of course >> without breaking migration. giving the guest only frame accuracy looks >> good to me. > > Ok, but then we need the shadow variable, iow then the patch stays as is > ... Can't we (a) switch frindex to microframe resolution, (b) round to frame resolution in pre_save and (c) return frindex & ~7 on guest register reads? cheers, Gerd