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 A26C8C433EF for ; Mon, 31 Jan 2022 15:24:31 +0000 (UTC) Received: from localhost ([::1]:59244 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nEYXe-0001lJ-Cx for qemu-devel@archiver.kernel.org; Mon, 31 Jan 2022 10:24:30 -0500 Received: from eggs.gnu.org ([209.51.188.92]:43066) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nEYV2-0007Ub-PR for qemu-devel@nongnu.org; Mon, 31 Jan 2022 10:21:48 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:56927) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nEYV0-0005D8-4x for qemu-devel@nongnu.org; Mon, 31 Jan 2022 10:21:47 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643642504; 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=YhB0Qjf7NDFI/PnjBQS8ALRT4bXYiJu1xQeX6seATrQ=; b=a6PaCKzYx4n/yPB6ggwIOeHksYEvhL3IdCulcZEgR5OLdHYR4KEQiy0TxiB7chNEuuDphM 2HaNym4m+VhlV05f20Fhh8MaoibVeM/NZvF+lboABhJpHDvEuRxRXqTdCd6snivvZqQ7Nd NejDW6gfKKcCfnJnHdQK0G/NWlEtRx0= 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-624-G5sDE_qYN8uJkUY65Ilhqw-1; Mon, 31 Jan 2022 10:21:41 -0500 X-MC-Unique: G5sDE_qYN8uJkUY65Ilhqw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5E04F1091DA1; Mon, 31 Jan 2022 15:21:40 +0000 (UTC) Received: from paraplu (unknown [10.39.195.135]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4A3E57DE26; Mon, 31 Jan 2022 15:21:39 +0000 (UTC) Date: Mon, 31 Jan 2022 16:21:36 +0100 From: Kashyap Chamarthy To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PATCH v2] docs: expand firmware descriptor to allow flash without NVRAM Message-ID: References: <20220131125509.170307-1-berrange@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kchamart@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=kchamart@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=-0.088, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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: , Cc: libvir-list@redhat.com, qemu-devel@nongnu.org, Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Jan 31, 2022 at 02:36:46PM +0000, Daniel P. Berrangé wrote: > On Mon, Jan 31, 2022 at 03:00:33PM +0100, Kashyap Chamarthy wrote: > > On Mon, Jan 31, 2022 at 12:55:09PM +0000, Daniel P. Berrangé wrote: [...] > > I briefly wondered if in this "combined" mode whether the no. of > > duplicate copies can ever fill up the storage. I doubt that, as the > > combined size of _VARS + _CODE is just about 2MB. So it only starts > > mattering if you're running tens of thousands of guests. > > When guest root / data disk sizes are measured in 100's of MB, or > GBs, I struggle to get worried about even a 16 MB OVMF blob being > copied per guest. Heh, fair enough. > The firmware can be provided in qcow2 format too, so if really > concerned, just create a qcow2 file with a backing store pointing > to the readonly master, so you're only paying the price of the > delta for any guest VARs writes. That's more efficient than what > we do today with copying the separate raw format VARS.fd file. That's nice, I didn't know the qcow2 possibility in this context. For some reason I assumed the file format always has to be raw here. Your qcow2 point above should be documented, if it isn't already. Although I don't know the right place for it. [...] -- /kashyap