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 9A245CCFA13 for ; Mon, 10 Nov 2025 13:54:29 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vISLR-0007P7-Hb; Mon, 10 Nov 2025 08:54:10 -0500 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 1vISAJ-0005W2-NR for qemu-devel@nongnu.org; Mon, 10 Nov 2025 08:42:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vISAF-0004qq-EM for qemu-devel@nongnu.org; Mon, 10 Nov 2025 08:42:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1762782153; 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=YhdkDoDLzl3DkAisWS71XVkKLFe4gnNlS8xdwLFj87Y=; b=clgKMeffRlNNGDJEatWP3JKiaAZQnD/AWadEFJe4w28Cz18cOBKIUeTDbqCC0l9kCiaode k0qBCNZlvQqlTjSYBVvUDtfLkiMeFp5XJxsWvUUf6fKlTSefRObgjGMN2mBo5P6nnEFG+I JB9bfyLfliL7Bk5zTsUa4oaxYqru+zQ= Received: from mx-prod-mc-05.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-617-gL0IHtNlMbGN22ugaF8lmA-1; Mon, 10 Nov 2025 08:42:32 -0500 X-MC-Unique: gL0IHtNlMbGN22ugaF8lmA-1 X-Mimecast-MFC-AGG-ID: gL0IHtNlMbGN22ugaF8lmA_1762782151 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1A45B1956094; Mon, 10 Nov 2025 13:42:31 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.18]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 85F5E1800451; Mon, 10 Nov 2025 13:42:30 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id CC7DD21E6A27; Mon, 10 Nov 2025 14:42:27 +0100 (CET) From: Markus Armbruster To: =?utf-8?Q?Cl=C3=A9ment?= Chigot Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, kwolf@redhat.com, hreitz@redhat.com, eblake@redhat.com Subject: Re: [PATCH v2 5/5] vvfat: add support for "fat-size" options In-Reply-To: (=?utf-8?Q?=22Cl=C3=A9ment?= Chigot"'s message of "Mon, 10 Nov 2025 14:26:46 +0100") References: <20251107145327.539481-1-chigot@adacore.com> <20251107145327.539481-6-chigot@adacore.com> <87zf8umbzh.fsf@pond.sub.org> <87bjlakpa5.fsf@pond.sub.org> Date: Mon, 10 Nov 2025 14:42:27 +0100 Message-ID: <87o6paj96k.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Cl=C3=A9ment Chigot writes: > On Mon, Nov 10, 2025 at 2:09=E2=80=AFPM Markus Armbruster wrote: >> >> Cl=C3=A9ment Chigot writes: >> >> > On Mon, Nov 10, 2025 at 11:13=E2=80=AFAM Markus Armbruster wrote: >> >> >> >> Cl=C3=A9ment Chigot writes: >> >> >> >> > This allows more flexibility to vvfat backend. The values of "Numbe= r of >> >> > Heads" and "Sectors per track" are based on SD specifications Part = 2. >> >> > >> >> > Due to the FAT architecture, not all sizes are reachable. Therefore= , it >> >> > could be round up to the closest available size. >> >> > >> >> > FAT32 has not been adjusted and thus still default to 504 Mib. >> >> > >> >> > For floppy, only 1440 Kib and 2880 Kib are supported. >> >> > >> >> > Signed-off-by: Cl=C3=A9ment Chigot >> >> >> >> [...] >> >> >> >> > diff --git a/qapi/block-core.json b/qapi/block-core.json >> >> > index 8a479ba090..0bcb360320 100644 >> >> > --- a/qapi/block-core.json >> >> > +++ b/qapi/block-core.json >> >> > @@ -3478,11 +3478,17 @@ >> >> > # (default: true) >> >> > # (since 10.2) >> >> > # >> >> > +# @fat-size: size of the device in bytes. Due to FAT underlying >> >> > +# architecture, this size can be rounded up to the closest val= id >> >> > +# size. >> >> > +# (since 10.2) >> >> > +# >> >> >> >> Can you explain again why you moved from @size to @fat-size? >> > >> > Just to be sure, you mean in the above comment, in the commit message = or both ? >> >> Just to me, because I'm not sure I like the change, but that may well be >> due to a lack of understanding of your reasons. > > Naming `fat-size` instead of `size` ensures the parameter is only > recognized by the vvfat backend. In particular, it will be refused by > the default raw format, avoiding confusion: > "-drive file=3Dfat:,size=3D256M" results in a 504M FAT disk > truncated to 256M, raw format being implicit. > "-drive file=3Dfat:,fat-size=3D256M" is refused. "fat-size" is > unsupported by raw format. I figure throwing in format=3Draw to make raw format explicit doesn't change anything. Correct? > "-drive file=3Dfat:,format=3Dvvfat,fat-size=3D256M" results in a 2= 56M FAT disk. > "-drive file=3Dfat:,format=3Dvvfat,size=3D256M" is refused. "size"= is > unsupported by vvfat format. If it was called @size, what behavior would we get? Just two cases, I think: 1. With raw format: -drive file=3Dfat:,size=3D256M 2. Without raw format: -drive file=3Dfat:,format=3Dvvfat,size=3D256M