From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44005) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1da1Ne-0004I6-2E for qemu-devel@nongnu.org; Tue, 25 Jul 2017 11:04:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1da1Nc-0003m5-Tu for qemu-devel@nongnu.org; Tue, 25 Jul 2017 11:04:14 -0400 References: <1500993699-19299-1-git-send-email-pl@kamp.de> <1500993699-19299-2-git-send-email-pl@kamp.de> From: Eric Blake Message-ID: Date: Tue, 25 Jul 2017 10:03:58 -0500 MIME-Version: 1.0 In-Reply-To: <1500993699-19299-2-git-send-email-pl@kamp.de> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="OA2D73PBbhCSdgi99abKiQvx7L6gkft1c" Subject: Re: [Qemu-devel] [PATCH V5 01/10] specs/qcow2: add compress format extension List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, kwolf@redhat.com, lersek@redhat.com, den@openvz.org, mreitz@redhat.com, berrange@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --OA2D73PBbhCSdgi99abKiQvx7L6gkft1c From: Eric Blake To: Peter Lieven , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, kwolf@redhat.com, lersek@redhat.com, den@openvz.org, mreitz@redhat.com, berrange@redhat.com Message-ID: Subject: Re: [PATCH V5 01/10] specs/qcow2: add compress format extension References: <1500993699-19299-1-git-send-email-pl@kamp.de> <1500993699-19299-2-git-send-email-pl@kamp.de> In-Reply-To: <1500993699-19299-2-git-send-email-pl@kamp.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 07/25/2017 09:41 AM, Peter Lieven wrote: > Signed-off-by: Peter Lieven > --- > docs/interop/qcow2.txt | 51 ++++++++++++++++++++++++++++++++++++++++++= +++++++- > roms/ipxe | 2 +- > 2 files changed, 51 insertions(+), 2 deletions(-) >=20 > + > +=3D=3D Compress format extension =3D=3D > + > +The compress format extension is an optional header extension. It prov= ides > +the ability to specify the compress algorithm and compress parameters s/the compress algorithm/the compression algorithm/ > +that are used for compressed clusters. This new header MUST be present= if > +the incompatible-feature bit "compress format bit" is set and MUST be = absent > +otherwise. > + > +The fields of the compress format extension are: > + > + Byte 0 - 13: compress_format_name (padded with zeros, but not > + necessarily null terminated if it has full length).= > + Valid compression format names currently are: > + > + deflate: Standard zlib deflate compression without > + compression header Why did you name it "deflate" instead of "zlib" again? > + > + 14: compress_level (uint8_t) > + > + 0 =3D default compress level (valid for all formats= , default) > + > + Additional valid compression levels for deflate com= pression: > + > + All values between 1 and 9. 1 gives best speed, 9 g= ives best > + compression. The default compression level is defin= ed by zlib > + and currently defaults to 6. > + > + 15: compress_window_size (uint8_t) > + > + Window or dictionary size used by the compression f= ormat. > + Currently only used by the deflate compression algo= rithm. What must this be set to for other algorithms? I guess we get to that in later patches. > + > + Valid window sizes for deflate compression range fr= om 8 to > + 15 inclusively. > + > +Note: Omitting the incompatible "Compress format bit" results in the u= sage > +of deflate compression with default compression level and a window siz= e of 12 > +(which was default before QEMU 2.11). If exactly these parameters are = choosen s/choosen/chosen,/ > +it is free to the implementation to omit the "Compress format bit" and= the s/it is free to the implementation to omit/the implementation may omit/ > +compress format extension when updating the QCOW2 header. > + > + > =3D=3D Host cluster management =3D=3D > =20 > qcow2 manages the allocation of host clusters by maintaining a referen= ce count > diff --git a/roms/ipxe b/roms/ipxe > index 0600d3a..b991c67 160000 > --- a/roms/ipxe > +++ b/roms/ipxe > @@ -1 +1 @@ > -Subproject commit 0600d3ae94f93efd10fc6b3c7420a9557a3a1670 > +Subproject commit b991c67c1d91574ef22336cc3a5944d1e63230c9 Oops. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --OA2D73PBbhCSdgi99abKiQvx7L6gkft1c Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAll3Xd4ACgkQp6FrSiUn Q2oDRAf/XuRQAEmFsTz+PPNLbGClgBrBOtZknpgYxr+/a6Q+nJyDIjzww8DUfbgT 7Aj2HNJ6IbdKkqv/skjA+mQ9GkNE04NhZZ8FPC5lVhYZuVPMXQgkojhq25YG33AQ 99lMqSF2AHpR8hOJoBJrKRmgTqPJ/Ai+n3XVW52TkLn7K5RKYpm1oYZ3R31SV5Ca LXRMbzC82slfO7lKH8t5gW0SNUGBhPB75IwS2Bz222S3CygMDykAODR6jRYzg1uk QsMLqkKaAEqmbo68zKR+XcLNXde8pdZf+WWmDvLifQtjPthw/DJOKymBQsYTJfMX 1iaoIK9VBOpsK1FIk6dX2FWug3EDOQ== =EQXL -----END PGP SIGNATURE----- --OA2D73PBbhCSdgi99abKiQvx7L6gkft1c--