From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:42593) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UPb9b-0003Cz-Sp for qemu-devel@nongnu.org; Tue, 09 Apr 2013 12:12:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UPb9Z-0006De-I9 for qemu-devel@nongnu.org; Tue, 09 Apr 2013 12:12:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32876) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UPb9Z-0006DJ-A5 for qemu-devel@nongnu.org; Tue, 09 Apr 2013 12:12:13 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r39GCCG0022643 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 9 Apr 2013 12:12:12 -0400 Message-ID: <51643DDB.1090309@redhat.com> Date: Tue, 09 Apr 2013 10:12:11 -0600 From: Eric Blake MIME-Version: 1.0 References: <87d2u3667x.fsf@blackfin.pond.sub.org> In-Reply-To: <87d2u3667x.fsf@blackfin.pond.sub.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="----enig2FWKCEFQTAXVWAREHSMKS" Subject: Re: [Qemu-devel] [PATCH v4 07/11] qapi: Convert savevm List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Pavel Hrdina , qemu-devel@nongnu.org, lcapitulino@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2FWKCEFQTAXVWAREHSMKS Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 04/09/2013 10:04 AM, Markus Armbruster wrote: >> + >> +## >> +# @vm-snapshot-save: >> +# >> +# Create a snapshot of the whole virtual machine. If tag is provided = as @name, >> +# it is used as human readable identifier. If there is already a snap= shot >> +# with the same tag or id, the force argument needs to be true to rep= lace it. >=20 > "tag or id"? >=20 > HMP command savevm's argument is matched against both QEMUSnapshotInfo > member id_str (a.k.a. id) and name (a.k.a. tag). Do we really want tha= t > kind of overloading in QMP? Shouldn't we make it tag vs. id explicit > there? The qcow2 file format already allows for the creation of a snapshot with an id but no tag. We've been back and forth about whether QMP should allow a user to be able to create all valid qcow2 files (and hence allow the omission of tag). But things really get confusing if you allow the creation of a tag that matches an existing id (create a snapshot, then create another snapshot with the tag '1'); or even if a tag can match a potential future id (create a snapshot with a tag named '2', then create another snapshot). So the lookup should always check for BOTH tag and id, even though the command is supplying only a 'tag'; and if a tag is omitted, a unique id will always be returned. >=20 >> +# >> +# The VM is automatically stopped and resumed and saving a snapshot c= an take >> +# a long time. >> +# >> +# @name: #optional tag of new snapshot or tag|id of existing snapshot= >=20 > Should we make this mandatory? We have to keep the argument optional i= n > HMP, but that needn't concern us here. If we mandate that a tag always be supplied, then we cannot create qcow2 files with a snapshot that lacks a tag using just QMP; but even if we do that, we STILL have to support use of existing qcow2 files that were created by earlier qemu and/or other tools that have snapshots without a tag. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org ------enig2FWKCEFQTAXVWAREHSMKS Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJRZD3bAAoJEKeha0olJ0Nq2XYH/iQy3FCwf1YQyugf1ceqYuPT TwsWyUgLSBDFUKSEGrDqXQeRYZX3ufbawxMD3I262QvCHmnT4X4BvgPNjvvoXZru 0Rl5JBqObeQd9/NhK51TcyI25yYpY4kaJZNB1aRin/JAthGZ/QmBvHXpRQsaKO+E t2b+f7p2Cpp5Hfk3VbjXAG5zk5DQr1mk8/WG7wpzjiTXKYn4ohD3/ofZON+MaBrr tOcb72zpacjwove/6oCORQMoOdf9swy1Z3Feo+afe02GbwpE2bvfHXvfwDv5sBFz M5vRWFhnKZ9HjwJRsiDEY/PCiSKXDTGU9mCamk1y9vB1oqUyeJeae+Fvdkwy7Lc= =CDoU -----END PGP SIGNATURE----- ------enig2FWKCEFQTAXVWAREHSMKS--