From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45432) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGakS-0005lx-Pq for qemu-devel@nongnu.org; Wed, 28 Jan 2015 17:06:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YGakN-0008IY-G3 for qemu-devel@nongnu.org; Wed, 28 Jan 2015 17:06:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49150) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YGakN-0008HV-6f for qemu-devel@nongnu.org; Wed, 28 Jan 2015 17:06:03 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t0SM5wNG001393 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Wed, 28 Jan 2015 17:06:02 -0500 Message-ID: <54C95D44.2060104@redhat.com> Date: Wed, 28 Jan 2015 15:05:56 -0700 From: Eric Blake MIME-Version: 1.0 References: <1422300468-16216-1-git-send-email-mreitz@redhat.com> <1422300468-16216-5-git-send-email-mreitz@redhat.com> <54C6A622.9010902@redhat.com> <54C6A6E4.8060000@redhat.com> <54C6AD3D.60808@redhat.com> <54C6AE02.4030105@redhat.com> <54C6B006.9000607@redhat.com> In-Reply-To: <54C6B006.9000607@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FThLHAl5b8xbLP0iS7bvVG1qCXwvNXJf6" Subject: Re: [Qemu-devel] [PATCH 04/21] block: Add bdrv_close_all() handlers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Max Reitz , qemu-devel@nongnu.org Cc: Kevin Wolf , Markus Armbruster , Stefan Hajnoczi This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --FThLHAl5b8xbLP0iS7bvVG1qCXwvNXJf6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 01/26/2015 02:22 PM, Paolo Bonzini wrote: >=20 >=20 > On 26/01/2015 22:13, Max Reitz wrote: >>>> >>> An eject blocker would also break backwards-compatibility though. Wh= at >>> about an eject notifier? Would that concept make sense? >> >> It does make sense (in that it is the way I would implement "just do >> what we always did"), but I just don't like it for the fact that it >> makes NBD a special snowflake. I can live with it, though. >=20 > Yes, it's weird. But this is just the backwards-compatible solution. >=20 > I'm okay with implementing only the new solution, but: >=20 > - the old QMP (and HMP?) commands must be removed Back-compat is a bear to figure out. From libvirt's perspective, it is okay to require a newer libvirt in order to drive newer qemu (the new libvirt knowing how to probe whether old or new commands exist, and use the right one); but it is still awkward any time upgrading qemu without libvirt causes things to break gratuitously. >=20 > - the new command probably must not reuse the same BB as the guest, and= > I am not sure that this is possible. We've had that design goal in the back of our minds for some time (sharing a single BDS among multiple devices) - but I don't think it has actually happened yet, so if this is the first time we make it happen, there may be lots of details to get right. But it makes the most sense (exporting and NBD disk is a form of creating a _new_ BB - distinct from a guest-visible device, but both uses are definitely backends; and sharing the same BDS among both backends makes total sense, so that the drive visible to the guest can change medium without invalidating the NBD serving up the old contents). --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --FThLHAl5b8xbLP0iS7bvVG1qCXwvNXJf6 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 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJUyV1FAAoJEKeha0olJ0NqflMH/jiiEi/0eJgCs1lHTg3bVEc6 OVq6sc3RllIJX40hP4sj/UdEW3KxMKfQnYSzZQ/hRzv3ZbzE0E4+Ai9xXgc+NCTI Fisc9mcEa8jeMuNP1UE5L+69zTkmXPTksp4irNyAXGQ+PMzo5zC3lL+p7TgXcGjl 7MueI49SyqSvvZ7oMbdtmsK4PhGUBU0DjIpdf0psS/BCFiVnGi0vTnr4vjqvoJsy FJ+ocknHgplws+6eqaHwwlXMl64tmDHj4X8mJ43kuJjPdo33d4AxJUVEXAKKHiz6 pn4YOlRCuQhzduSqybKR4HYTE1pSvk2F8QKSeAWqlao7tIU2Z9/GTfblSQModZ8= =LyjD -----END PGP SIGNATURE----- --FThLHAl5b8xbLP0iS7bvVG1qCXwvNXJf6--