From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 844AFC433E0 for ; Thu, 16 Jul 2020 06:44:12 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 56246206F5 for ; Thu, 16 Jul 2020 06:44:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 56246206F5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=ispras.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39986 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jvxcp-0007vL-LL for qemu-devel@archiver.kernel.org; Thu, 16 Jul 2020 02:44:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58316) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jvxc9-0007U8-8h for qemu-devel@nongnu.org; Thu, 16 Jul 2020 02:43:29 -0400 Received: from mail.ispras.ru ([83.149.199.84]:39932) by eggs.gnu.org with esmtps (TLS1.2:DHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jvxc6-00080A-5j for qemu-devel@nongnu.org; Thu, 16 Jul 2020 02:43:28 -0400 Received: from [192.168.0.183] (unknown [62.118.151.149]) by mail.ispras.ru (Postfix) with ESMTPSA id 1414440AAD8E; Thu, 16 Jul 2020 06:43:23 +0000 (UTC) Subject: Re: [PATCH 02/13] qcow2: introduce icount field for snapshots To: Eric Blake , qemu-devel@nongnu.org References: <159316678008.10508.6615172353109944370.stgit@pasha-ThinkPad-X280> <159316679154.10508.16814264064541947914.stgit@pasha-ThinkPad-X280> <6882cb05-8533-d6ac-d41b-95c3d19ca496@redhat.com> From: Pavel Dovgalyuk Message-ID: <307693af-4dfd-17d3-0efa-1acb30158e35@ispras.ru> Date: Thu, 16 Jul 2020 09:43:22 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <6882cb05-8533-d6ac-d41b-95c3d19ca496@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=83.149.199.84; envelope-from=pavel.dovgalyuk@ispras.ru; helo=mail.ispras.ru X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/16 02:00:58 X-ACL-Warn: Detected OS = Linux 3.11 and newer X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, ehabkost@redhat.com, philmd@redhat.com, mtosatti@redhat.com, stefanha@redhat.com, armbru@redhat.com, mreitz@redhat.com, wrampazz@redhat.com, crosa@redhat.com, pbonzini@redhat.com, alex.bennee@linaro.org, zhiwei_liu@c-sky.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 06.07.2020 23:17, Eric Blake wrote: > On 6/26/20 5:19 AM, Pavel Dovgalyuk wrote: >> From: Pavel Dovgalyuk >> >> This patch introduces the icount field for saving within the snapshot. >> It is required for navigation between the snapshots in record/replay >> mode. >> >> Signed-off-by: Pavel Dovgalyuk >> Acked-by: Kevin Wolf >> --- >>   0 files changed >> > > That's an odd diffstat; you may want to investigate why git isn't > showing the usual diffstat that makes it easier to see which files are > touched and the relative size of the changes. Thanks for noticing, that was a stgit bug. >> +++ b/docs/interop/qcow2.txt >> @@ -645,6 +645,11 @@ Snapshot table entry: >>                       Byte 48 - 55:   Virtual disk size of the >> snapshot in bytes >> +                    Byte 56 - 63:   icount value which corresponds to >> +                                    the record/replay instruction count >> +                                    when the snapshot was taken. Set >> to -1 >> +                                    if icount was disabled >> + >>                       Version 3 images must include extra data at >> least up to >>                       byte 55. > > Should we have additional text here, similar to what was added to the > overall header in 3ae3fcfa, about how to properly add additional > optional fields while maintaining back-compat considerations?  Maybe > just a one sentence reference that the rules in that section apply here > too? Your proposal is adding more details about header extension in that patch? But I didn't get what exactly is needed, because there is already the following text in the beginning of "variable" part: variable: Extra data for future extensions. Unknown fields must be ignored. Currently defined are (offset relative to snapshot table entry): Pavel Dovgalyuk