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 1F6C6CCD1BC for ; Thu, 23 Oct 2025 18:21:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vBzw2-0002CD-2H; Thu, 23 Oct 2025 14:21:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vBzvt-0002AZ-SN for qemu-devel@nongnu.org; Thu, 23 Oct 2025 14:21:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vBzvr-0006Us-I1 for qemu-devel@nongnu.org; Thu, 23 Oct 2025 14:21:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761243661; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tpvw1ocDqVJ6iJOZ/XM4STlfLgrjUCg2rMhKsgkLDp0=; b=VVCn8oYyW2Yea1aR0vqwOe7cz+28BzQKEpmdDfC9ChGY0S40iszn51j6EJJybbmLpbpC/Y Nb9cd7niGSaCv1qMCNPwYezBX6FNzAIOgIq7Hy3CPY6cWLJYAzoKohfDp9hfol0u/JbVt8 JEZm0zO2zvPA+LeSaGre6qNLgvSrVHU= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-496-BraGkLnwNTi21S2NyBwY8Q-1; Thu, 23 Oct 2025 14:20:59 -0400 X-MC-Unique: BraGkLnwNTi21S2NyBwY8Q-1 X-Mimecast-MFC-AGG-ID: BraGkLnwNTi21S2NyBwY8Q_1761243657 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 03368195609D; Thu, 23 Oct 2025 18:20:57 +0000 (UTC) Received: from redhat.com (unknown [10.45.225.90]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3EC633000B50; Thu, 23 Oct 2025 18:20:54 +0000 (UTC) Date: Thu, 23 Oct 2025 20:20:51 +0200 From: Kevin Wolf To: =?iso-8859-1?Q?Cl=E9ment?= Chigot Cc: qemu-devel@nongnu.org, hreitz@redhat.com, qemu-block@nongnu.org Subject: Re: [PATCH 1/5] vvfat: introduce no-mbr option Message-ID: References: <20250903075721.77623-1-chigot@adacore.com> <20250903075721.77623-2-chigot@adacore.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250903075721.77623-2-chigot@adacore.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Am 03.09.2025 um 09:57 hat Clément Chigot geschrieben: > This option when set prevents a master boot record (MBR) to be > initialized. This is mandatory as some operating system don't recognized > mounted disks if a MBR is present. > > Signed-off-by: Clément Chigot Can we actually give an example of such an OS in the commit message? > --- > block/vvfat.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/block/vvfat.c b/block/vvfat.c > index 814796d918..0220dd828b 100644 > --- a/block/vvfat.c > +++ b/block/vvfat.c > @@ -1082,6 +1082,11 @@ static QemuOptsList runtime_opts = { > .type = QEMU_OPT_BOOL, > .help = "Make the image writable", > }, > + { > + .name = "no-mbr", > + .type = QEMU_OPT_BOOL, > + .help = "Do not add a Master Boot Record on this disk", > + }, Let's keep option names positive to avoid double negations like 'no-mbr=false'. We can have an 'mbr' option that defaults to true. Or in fact, maybe calling it 'partitioned' would be easier to understand. You need to update BlockdevOptionsVVFAT in qapi/block-core.json, too, to make the new option work with -blockdev. You should update the description for @floppy there, too, because it says that hard disks are always partitioned. It should also be added to vvfat_strong_runtime_opts because the value of this option changes the data that the guest sees. > { /* end of list */ } > }, > }; > @@ -1092,6 +1097,7 @@ static void vvfat_parse_filename(const char *filename, QDict *options, > int fat_type = 0; > bool floppy = false; > bool rw = false; > + bool no_mbr = false; > int i; > > if (!strstart(filename, "fat:", NULL)) { > @@ -1116,6 +1122,10 @@ static void vvfat_parse_filename(const char *filename, QDict *options, > rw = true; > } > > + if (strstr(filename, ":no-mbr:")) { In the string, the negative form can stay (because the positive one doesn't exist here). > + no_mbr = true; > + } > + > /* Get the directory name without options */ > i = strrchr(filename, ':') - filename; > assert(i >= 3); > @@ -1131,6 +1141,7 @@ static void vvfat_parse_filename(const char *filename, QDict *options, > qdict_put_int(options, "fat-type", fat_type); > qdict_put_bool(options, "floppy", floppy); > qdict_put_bool(options, "rw", rw); > + qdict_put_bool(options, "no-mbr", no_mbr); > } > > static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, > @@ -1196,7 +1207,10 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, > if (!s->fat_type) { > s->fat_type = 16; > } > - s->offset_to_bootsector = 0x3f; > + /* Reserver space for MBR */ > + if (!qemu_opt_get_bool(opts, "no-mbr", false)) { > + s->offset_to_bootsector = 0x3f; > + } > cyls = s->fat_type == 12 ? 64 : 1024; > heads = 16; > secs = 63; Kevin