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 0A3BCCCD183 for ; Thu, 9 Oct 2025 07:14:42 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v6kqc-0005cO-Ad; Thu, 09 Oct 2025 03:13:58 -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 1v6kqY-0005cF-RQ for qemu-devel@nongnu.org; Thu, 09 Oct 2025 03:13:55 -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 1v6kqO-0008Hm-A2 for qemu-devel@nongnu.org; Thu, 09 Oct 2025 03:13:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759994016; h=from:from:reply-to: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=5AQECQi/clLIPCy9kCXS2O4tx6Q9lBKFtFWizvFuCSI=; b=VLr7m6Ygq+xGbOd+8IShDCifrqpEyeSLpP+pmZFqcYDMvQFxZ7W3blvI+hPurmNTJCQqhF b6W3nfCSSMPu4MWYk7HFpFhhkWYwf77UjPkJh36IHVlBA3P/XV/5FnM2vh7ATbotxBAgC2 82cQ6Ummos6OGVAOuhYCEqgGKd5NAhE= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-665-hqn91yQbMZerKajzWHMwmQ-1; Thu, 09 Oct 2025 03:13:33 -0400 X-MC-Unique: hqn91yQbMZerKajzWHMwmQ-1 X-Mimecast-MFC-AGG-ID: hqn91yQbMZerKajzWHMwmQ_1759994011 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2D2301800298; Thu, 9 Oct 2025 07:13:30 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.63]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0CC831800447; Thu, 9 Oct 2025 07:13:25 +0000 (UTC) Date: Thu, 9 Oct 2025 08:13:22 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. David Alan Gilbert" Cc: Gerd Hoffmann , qemu-devel@nongnu.org, Laurent Vivier , Marcel Apfelbaum , Markus Armbruster , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Yanan Wang , Paolo Bonzini , Fabiano Rosas , Eric Blake , Eduardo Habkost , Zhao Liu Subject: Re: [PATCH v2] hw/uefi: add "info ovmf-log" + "query-ovmf-log" monitor commands Message-ID: References: <20251007135216.1687648-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@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, 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, T_SPF_TEMPERROR=0.01 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Oct 09, 2025 at 01:56:09AM +0000, Dr. David Alan Gilbert wrote: > * Gerd Hoffmann (kraxel@redhat.com) wrote: > > Starting with the edk2-stable202508 tag OVMF (and ArmVirt too) have > > optional support for logging to a memory buffer. There is guest side > > support -- for example in linux kernels v6.17+ -- to read that buffer. > > But that might not helpful if your guest stops booting early enough that > > guest tooling can not be used yet. So host side support to read that > > log buffer is a useful thing to have. > > > > This patch implements both qmp and hmp monitor commands to read the > > firmware log. > > > > Signed-off-by: Gerd Hoffmann > > I'm OK with that, but I wonder if it would be better to have a command > that wrote the buffer to a file rather than displaying it directly; I don't > think we normally have anything else which outputs that much raw guest > provided data directly. > I assume when it goes wrong you end up with random unprintable junk in > the buffer. 128 KB is on the high side, but is not terrible. Libvirt (arbitrarily) caps a QMP reply at 10 MB. Libvirt is going to want to send this on to the client app and will likely do that streaming in memory, so having it iin a file is not required from our POV. IIRC, some of the query-block command replies can get insanely huge when the qcow2 chain is very long. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|