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 lists1p.gnu.org (lists1p.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 3ACC8C44507 for ; Tue, 14 Jul 2026 10:47:46 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wjafi-0004qa-UZ; Tue, 14 Jul 2026 06:47:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wjafe-0004oz-VJ for qemu-devel@nongnu.org; Tue, 14 Jul 2026 06:47:28 -0400 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 1wjafd-0002oD-78 for qemu-devel@nongnu.org; Tue, 14 Jul 2026 06:47:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784026044; 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=WQ3dQ1n5tCQBSG7SlIqJQBftmYve5Yicvpr6+M6czGE=; b=TDdmmRSujjWszMTjuJci9Ef3EapIN9JWvCDxH5bmC9pawgrVB1SC61532e6DBLaPr8dCB2 6MJ+5HSQ75aINO/vZBWiQ48kR4n8sFIes7YJW0bEA/pjlkU1QRY/khFcHUWD53Luo2XlRf HTi+95IckqwpayFV8Z0p7hlHsigNHtY= Received: from mx-prod-mc-03.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-593-bjes10DyMyWOlpyaKll-Aw-1; Tue, 14 Jul 2026 06:47:21 -0400 X-MC-Unique: bjes10DyMyWOlpyaKll-Aw-1 X-Mimecast-MFC-AGG-ID: bjes10DyMyWOlpyaKll-Aw_1784026040 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 77E82195605A; Tue, 14 Jul 2026 10:47:20 +0000 (UTC) Received: from redhat.com (unknown [10.44.33.162]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 71F4E180049F; Tue, 14 Jul 2026 10:47:18 +0000 (UTC) Date: Tue, 14 Jul 2026 12:47:16 +0200 From: Kevin Wolf To: Thomas Huth Cc: qemu-block@nongnu.org, Hanna Reitz , qemu-devel@nongnu.org, armbru@redhat.com Subject: Re: [PATCH] block: Print simple help text when calling "-blockdev help" Message-ID: References: <20260710093654.466642-1-thuth@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260710093654.466642-1-thuth@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: permerror client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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_H2=-0.01, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, T_SPF_PERMERROR=0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 10.07.2026 um 11:36 hat Thomas Huth geschrieben: > From: Thomas Huth > > Other command line options like "-chardev", "-netdev" or "-device" > already present the user with a list of available parameters, but > when running "-blockdev help", there is currently only an error > message. There is already the possibility to run "-drive format=help", > but it does not seem to be documented, so this is not very useful > for the average user. Let's improve this situation by providing > the same list of available drivers when running QEMU with > "-blockdev help". > > Signed-off-by: Thomas Huth Seems like a good idea to print at least some minimal help there. However, I find the list from -drive format=help quite hard to read, and repeating the same list twice for read-write and read-only doesn't help either. I don't expect we can change -drive because I seem to remember that management tools look at it, but can we make -blockdev help more consistent with the other examples you mention? Something like this: Available blockdev drivers: blkdebug blklogwrites (read-only) blkreplay ... Ideally, I'd also love to have a way to show all the options a specific driver offers, but that probably won't happen before Markus QAPIfies the CLI. :-) > include/block/block-common.h | 1 + > blockdev.c | 15 ++++++++++----- > system/vl.c | 7 +++++-- > 3 files changed, 16 insertions(+), 7 deletions(-) > > diff --git a/include/block/block-common.h b/include/block/block-common.h > index 895ea175413..010c4425dcf 100644 > --- a/include/block/block-common.h > +++ b/include/block/block-common.h > @@ -583,5 +583,6 @@ char *path_combine(const char *base_path, const char *filename); > char *bdrv_get_full_backing_filename_from_filename(const char *backed, > const char *backing, > Error **errp); > +void blockdev_show_help(void); > > #endif /* BLOCK_COMMON_H */ > diff --git a/blockdev.c b/blockdev.c > index 6e86c6262f9..3d179939205 100644 > --- a/blockdev.c > +++ b/blockdev.c > @@ -475,6 +475,15 @@ static OnOffAuto account_get_opt(QemuOpts *opts, const char *name) > return ON_OFF_AUTO_OFF; > } > > +void blockdev_show_help(void) > +{ > + qemu_printf("Supported formats:"); We should definitely talk about "drivers" rather than "formats" with -blockdev. The help in -drive was added in QEMU 0.10 when "formats" was actually still accurate, but it hasn't been for a long time. > + bdrv_iterate_format(bdrv_format_print, NULL, false); > + qemu_printf("\nSupported formats (read-only):"); > + bdrv_iterate_format(bdrv_format_print, NULL, true); > + qemu_printf("\n"); > +} > + > /* Takes the ownership of bs_opts */ > static BlockBackend *blockdev_init(const char *file, QDict *bs_opts, > Error **errp) > @@ -541,11 +550,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts, > > if ((buf = qemu_opt_get(opts, "format")) != NULL) { > if (is_help_option(buf)) { > - qemu_printf("Supported formats:"); > - bdrv_iterate_format(bdrv_format_print, NULL, false); > - qemu_printf("\nSupported formats (read-only):"); > - bdrv_iterate_format(bdrv_format_print, NULL, true); > - qemu_printf("\n"); > + blockdev_show_help(); > goto early_err; > } > > diff --git a/system/vl.c b/system/vl.c > index 061cbdf860b..40c0593154a 100644 > --- a/system/vl.c > +++ b/system/vl.c > @@ -2961,7 +2961,10 @@ void qemu_init(int argc, char **argv) > HD_OPTS); > break; > case QEMU_OPTION_blockdev: > - { > + if (is_help_option(optarg)) { > + blockdev_show_help(); > + exit(EXIT_SUCCESS); > + } else { > Visitor *v; > BlockdevOptionsQueueEntry *bdo; > > @@ -2974,8 +2977,8 @@ void qemu_init(int argc, char **argv) > visit_free(v); > loc_save(&bdo->loc); > QSIMPLEQ_INSERT_TAIL(&bdo_queue, bdo, entry); > - break; > } > + break; > case QEMU_OPTION_drive: > if (!qemu_opts_parse_noisily(qemu_find_opts("drive"), > optarg, false)) { > -- > 2.55.0 Kevin