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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C135C47409 for ; Mon, 16 Dec 2019 12:19:14 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 1563B206CB for ; Mon, 16 Dec 2019 12:19:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1563B206CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52596 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1igpLE-00020k-Rj for qemu-devel@archiver.kernel.org; Mon, 16 Dec 2019 07:19:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:49370) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1igpJp-0000Wi-Hb for qemu-devel@nongnu.org; Mon, 16 Dec 2019 07:17:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1igpJn-0001rp-TL for qemu-devel@nongnu.org; Mon, 16 Dec 2019 07:17:45 -0500 Received: from relay.sw.ru ([185.231.240.75]:33562) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1igpJn-0001r9-M5; Mon, 16 Dec 2019 07:17:43 -0500 Received: from vovaso.qa.sw.ru ([10.94.3.0] helo=kvm.qa.sw.ru) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1igpJe-00033D-Gr; Mon, 16 Dec 2019 15:17:34 +0300 From: Vladimir Sementsov-Ogievskiy To: qemu-devel@nongnu.org Subject: [PATCH v9 2/2] docs: qcow2: introduce compression type feature Date: Mon, 16 Dec 2019 15:17:33 +0300 Message-Id: <20191216121733.63562-3-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20191216121733.63562-1-vsementsov@virtuozzo.com> References: <20191216121733.63562-1-vsementsov@virtuozzo.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 185.231.240.75 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, vsementsov@virtuozzo.com, qemu-block@nongnu.org, armbru@redhat.com, mreitz@redhat.com, dplotnikov@virtuozzo.com, den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The patch add new additional field to qcow2 header: compression_type, which specifies compression type. If field is absent or zero, default compression type is set: ZLIB, which corresponds to current behavior. New compression type (ZSTD) is to be added in further commit. Suggested-by: Denis Plotnikov Signed-off-by: Vladimir Sementsov-Ogievskiy --- docs/interop/qcow2.txt | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt index d92c827763..77146b5169 100644 --- a/docs/interop/qcow2.txt +++ b/docs/interop/qcow2.txt @@ -109,6 +109,11 @@ the next fields through header_length. An External Data File Name header extension may be present if this bit is set. + Bit 3: Compression type bit. If this bit is set, + non-default compression is used for compressed + clusters. compression_type field must be + present and not zero. + Bits 3-63: Reserved (set to 0) 80 - 87: compatible_features @@ -188,7 +193,16 @@ present*, if not altered by specific incompatible bit. *. Field is not present when header_length is less or equal to field's offset. Also, all additional fields are not present for version 2. - < ... No additional fields in the header currently ... > + 104: compression_type + Defines the compression method used for compressed clusters. + A single compression type is applied to all compressed image + clusters. + If incompatible compression type bit is set: the field must + be present and non-zero (which means non-zlib compression type) + If incompatible compression type bit is unset: the field + may not exist or it must be zero (which means zlib). + Available compression type values: + 0: zlib Header padding -- 2.18.0