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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 20CABC433FE for ; Tue, 1 Feb 2022 15:19:07 +0000 (UTC) Received: from localhost ([::1]:33516 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nEuvy-0006HT-J4 for qemu-devel@archiver.kernel.org; Tue, 01 Feb 2022 10:19:06 -0500 Received: from eggs.gnu.org ([209.51.188.92]:52836) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nEsYk-0000L1-Aj for qemu-devel@nongnu.org; Tue, 01 Feb 2022 07:46:58 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:55059) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nEsYe-0002ap-Iw for qemu-devel@nongnu.org; Tue, 01 Feb 2022 07:46:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643719526; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LNTVb7q+HaWpkfq33rfrxk373PF4oDyG6jZnW1mPjMI=; b=ALmjW7ruUptTbG70S4RMjoGnZwoo1DAP1kBti7gFF2gitDmRbskJblO73ubgTbn46HtPgR 2+i+bwief0wv2rFIQvUMpNxdPcs1au8q88Ql0R9kZ1FElZ2uu/sujaXjCcVFkR4dz4vNHc y4mnNFx17D/NdBda6dedJEVrDp4K2F0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-88-7-uOOYnKMLelB58SOv5IFA-1; Tue, 01 Feb 2022 07:45:23 -0500 X-MC-Unique: 7-uOOYnKMLelB58SOv5IFA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A3FAE101F002; Tue, 1 Feb 2022 12:45:22 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.45]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C489F752A0; Tue, 1 Feb 2022 12:45:01 +0000 (UTC) Date: Tue, 1 Feb 2022 13:44:59 +0100 From: Kevin Wolf To: Hanna Reitz Subject: Re: [PATCH] qemu-img: Unify [-b [-F]] documentation Message-ID: References: <20220131135908.32393-1-hreitz@redhat.com> MIME-Version: 1.0 In-Reply-To: <20220131135908.32393-1-hreitz@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.081, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eric Blake , qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 31.01.2022 um 14:59 hat Hanna Reitz geschrieben: > qemu-img convert documents the backing file and backing format options > as follows: > [-B backing_file [-F backing_fmt]] > whereas qemu-img create has this: > [-b backing_file] [-F backing_fmt] > > That is, for convert, we document that -F cannot be given without -B, > while for create, way say that they are independent. > > Indeed, it is technically possible to give -F without -b, because it is > left to the block driver to decide whether this is an error or not, so > sometimes it is: > > $ qemu-img create -f qed -F qed test.qed 64M > Formatting 'test.qed', fmt=qed size=67108864 backing_fmt=qed [...] > > And sometimes it is not: > > $ qemu-img create -f qcow2 -F qcow2 test.qcow2 64M > Formatting 'test.qcow2', fmt=qcow2 cluster_size=65536 [...] > qemu-img: test.qcow2: Backing format cannot be used without backing file > > Generally, it does not make much sense, though, and users should only > give -F with -b, so document it that way, as we have already done for > qemu-img convert (commit 1899bf47375ad40555dcdff12ba49b4b8b82df38). > > Reported-by: Tingting Mao > Signed-off-by: Hanna Reitz Thanks, applied to the block branch. Kevin