From patchwork Wed Jul 11 01:22:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 942289 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 41QLt96x4nz9s0W for ; Wed, 11 Jul 2018 11:23:12 +1000 (AEST) Received: from localhost ([::1]:50944 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fd3qX-00068Z-DX for incoming@patchwork.ozlabs.org; Tue, 10 Jul 2018 21:23:09 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47885) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fd3q7-00067K-Ad for qemu-devel@nongnu.org; Tue, 10 Jul 2018 21:22:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fd3q6-0002e3-Gl for qemu-devel@nongnu.org; Tue, 10 Jul 2018 21:22:43 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49142 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fd3q0-0002U6-Dc; Tue, 10 Jul 2018 21:22:36 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AED15407048D; Wed, 11 Jul 2018 01:22:35 +0000 (UTC) Received: from lemon.usersys.redhat.com (ovpn-12-108.pek2.redhat.com [10.72.12.108]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4F2F1111D3CE; Wed, 11 Jul 2018 01:22:32 +0000 (UTC) From: Fam Zheng To: qemu-devel@nongnu.org Date: Wed, 11 Jul 2018 09:22:27 +0800 Message-Id: <20180711012227.31600-1-famz@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 11 Jul 2018 01:22:35 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 11 Jul 2018 01:22:35 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'famz@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH] qemu-img: Document copy offloading implications with -S and -c X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Explicitly enabling zero detection or compression suppresses copy offloading during convert. Document it. Suggested-by: Kevin Wolf Signed-off-by: Fam Zheng Reviewed-by: Stefan Hajnoczi --- qemu-img.texi | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/qemu-img.texi b/qemu-img.texi index aeb1b9e66c..5853cd18d1 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -96,7 +96,8 @@ will enumerate information about backing files in a disk image chain. Refer below for further description. @item -c -indicates that target image must be compressed (qcow format only) +indicates that target image must be compressed (qcow format only). If this +option is used, copy offloading will not be attempted. @item -h with or without a command shows help and lists the supported formats @@ -115,7 +116,8 @@ in case both @var{-q} and @var{-p} options are used. indicates the consecutive number of bytes that must contain only zeros for qemu-img to create a sparse image during conversion. This value is rounded down to the nearest 512 bytes. You may use the common size suffixes like -@code{k} for kilobytes. +@code{k} for kilobytes. If this option is used, copy offloading will not be +attempted. @item -t @var{cache} specifies the cache mode that should be used with the (destination) file. See