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 0A54CC54EBC for ; Tue, 10 Jan 2023 15:12:25 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pFFIi-0008Bw-7n; Tue, 10 Jan 2023 09:08:28 -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 1pFFIf-0008Ak-Cp for qemu-devel@nongnu.org; Tue, 10 Jan 2023 09:08:25 -0500 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 1pFFId-0004gR-Uk for qemu-devel@nongnu.org; Tue, 10 Jan 2023 09:08:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673359703; 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=S53fopYlto7GATnEBLPdwchlTbAjmE+Zrf3fu00VL9U=; b=JSNneCK13qC1TfrGvw+kxiCd4o0gBWce98ST8NYcztFd1J38fQg8bdtFaByDbs4SMK2FLy Nv14v7aI9oR2YIfBVhmGWhhkShod1TZ5y1yL9XXsZ1FPXtG5JQVN9lNi5SgITkLDzRyJCQ EGK61egIHFZxL4Yf4YmjAmN2VPiHXls= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-538-lbQzg5JzOeqnyA1bzBhYXg-1; Tue, 10 Jan 2023 09:08:20 -0500 X-MC-Unique: lbQzg5JzOeqnyA1bzBhYXg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 09AFF80557C; Tue, 10 Jan 2023 14:08:08 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4C93A422FE; Tue, 10 Jan 2023 14:08:06 +0000 (UTC) Date: Tue, 10 Jan 2023 15:08:04 +0100 From: Kevin Wolf To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Peter Maydell , qemu-arm@nongnu.org, Hanna Reitz , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , John Snow , Kashyap Chamarthy , Xiang Zheng Subject: Re: [PATCH v2] pflash: Only read non-zero parts of backend image Message-ID: References: <20221220084246.1984871-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221220084246.1984871-1-kraxel@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 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_H2=-0.001, SPF_HELO_NONE=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 20.12.2022 um 09:42 hat Gerd Hoffmann geschrieben: > From: Xiang Zheng > > Currently we fill the VIRT_FLASH memory space with two 64MB NOR images > when using persistent UEFI variables on virt board. Actually we only use > a very small(non-zero) part of the memory while the rest significant > large(zero) part of memory is wasted. > > So this patch checks the block status and only writes the non-zero part > into memory. This requires pflash devices to use sparse files for > backends. > > Signed-off-by: Xiang Zheng > > [ kraxel: rebased to latest master ] > > Signed-off-by: Gerd Hoffmann Thanks, applied to the block branch. Even though discussion is ongoing about using alternative devices, it seems to me that this is a simple optimisation that doesn't change the behaviour as seen by the guest and that we want to have either way. If anyone objects and wants me to drop the patch again, let me know. Kevin