From nobody Tue Apr 15 14:48:21 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1582214988; cv=none; d=zohomail.com; s=zohoarc; b=UrHeuKCQpvQPK/w/KpQWeDrR7m/9rbwZ82vV60ZN8vRU2JqrnUpJcHWBhRyBlPHKkTXHgneIEz0auqYA15c0i2M+ZXmS0ycLnZjCAVnXKahQnlp2lch+L35/ikknZ4KaQ2Vp0B6mrdlhGQ/yISELvSQH4+69NAcyDJQtqyw7A/M= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1582214988; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=OhMxv/IG+GIdXRB2FTwhfQ52TVogWpuaqU23iG/opWM=; b=kSuV2xS5Kll+d7Y8D8trOY5drcg+nUBo1xHvP6szif/UD10tzYzqK2+iF/1imnDbFV6MYDDT5EuLqxvlEn8IS3LHcEuJ46HI26R4dSVLi21Hygbpvmfr5ff8HNKTMx4xR6yJXz6pSCO9/r3kqHO2JaG2XKLA90hzFpctoA+O82E= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 158221498893160.410782808429985; Thu, 20 Feb 2020 08:09:48 -0800 (PST) Received: from localhost ([::1]:45036 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j4oOZ-0004CS-59 for importer@patchew.org; Thu, 20 Feb 2020 11:09:47 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:54612) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j4oN9-0002Xa-Lo for qemu-devel@nongnu.org; Thu, 20 Feb 2020 11:08:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j4oN8-0004nM-41 for qemu-devel@nongnu.org; Thu, 20 Feb 2020 11:08:19 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:43167 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j4oN8-0004mt-0Y for qemu-devel@nongnu.org; Thu, 20 Feb 2020 11:08:18 -0500 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-237-Bhe8QZU4OeeGseZZwQ1TCQ-1; Thu, 20 Feb 2020 11:08:08 -0500 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 8AFC9800D53; Thu, 20 Feb 2020 16:08:07 +0000 (UTC) Received: from localhost (unknown [10.36.118.38]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AD6DF5C1B0; Thu, 20 Feb 2020 16:08:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582214897; 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=OhMxv/IG+GIdXRB2FTwhfQ52TVogWpuaqU23iG/opWM=; b=TkWFfmfCKtl0H1PbSG6hj/kJVmXZtGEIHDMq8B8gb9nJHrCgTT4pDdG6LRsTrfBZTxwXq1 pedTIBL9wVzymxn6BsSRmGe92XLXM96MO1L1eCfLQ5hGs7iUMS2zAFRtNA1zjr5we6Anoo BZsd5IGbvYY4R7kejUyL05JYJxceotc= From: Max Reitz To: qemu-block@nongnu.org Subject: [PULL 02/18] docs: qcow2: introduce compression type feature Date: Thu, 20 Feb 2020 17:06:54 +0100 Message-Id: <20200220160710.533297-3-mreitz@redhat.com> In-Reply-To: <20200220160710.533297-1-mreitz@redhat.com> References: <20200220160710.533297-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-MC-Unique: Bhe8QZU4OeeGseZZwQ1TCQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: Kevin Wolf , Peter Maydell , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Vladimir Sementsov-Ogievskiy The patch adds a new additional field to the 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 Message-Id: <20200131142219.3264-3-vsementsov@virtuozzo.com> [mreitz: s/Bits 3-63: Reserved/Bits 4-63: Reserved/] Signed-off-by: Max Reitz --- docs/interop/qcow2.txt | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt index 823cc266e0..5597e24474 100644 --- a/docs/interop/qcow2.txt +++ b/docs/interop/qcow2.txt @@ -109,7 +109,12 @@ the next fields through header_length. An External Data File Name header extensio= n may be present if this bit is set. =20 - Bits 3-63: Reserved (set to 0) + Bit 3: Compression type bit. If this bit is set, + a non-default compression is used for comp= ressed + clusters. The compression_type field must = be + present and not zero. + + Bits 4-63: Reserved (set to 0) =20 80 - 87: compatible_features Bitmask of compatible features. An implementation can @@ -190,7 +195,19 @@ present*, if not altered by a specific incompatible bi= t. to the field's offset. Also, all additional fields are not present for version 2. =20 - < ... No additional fields in the header currently ... > + 104: compression_type + + Defines the compression method used for compressed clu= sters. + All compressed clusters in an image use the same compr= ession + type. + + If the incompatible bit "Compression type" is set: the= field + must be present and non-zero (which means non-zlib + compression type). Otherwise, this field must not be p= resent + or must be zero (which means zlib). + + Available compression type values: + 0: zlib =20 =20 =3D=3D=3D Header padding =3D=3D=3D --=20 2.24.1