From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:58867) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ghJDL-0000RU-AU for qemu-devel@nongnu.org; Wed, 09 Jan 2019 14:08:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ghJ7e-0007jQ-Qi for qemu-devel@nongnu.org; Wed, 09 Jan 2019 14:02:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35972) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ghJ7c-0007g3-Nm for qemu-devel@nongnu.org; Wed, 09 Jan 2019 14:02:38 -0500 References: <20180906111107.30684-1-danielhb413@gmail.com> <47023eb5-41f1-1b60-1094-d607999e93b6@redhat.com> <200ecea3-1ef4-3ecf-6b37-f6e45fef3849@redhat.com> <20190109172023.GK4867@localhost.localdomain> <40ef0a8d-3a25-4cc3-95f8-82bc4513776c@redhat.com> <20190109185154.GL4867@localhost.localdomain> From: Eric Blake Message-ID: <56880d06-a214-2486-2e80-c565b33461b3@redhat.com> Date: Wed, 9 Jan 2019 13:02:34 -0600 MIME-Version: 1.0 In-Reply-To: <20190109185154.GL4867@localhost.localdomain> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="asvhtkiiczUXV3OKguL80zXlPR2bRHJB0" Subject: Re: [Qemu-devel] [PATCH v2 0/3] HMP/snapshot changes - do not use ID anymore List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: Max Reitz , armbru@redhat.com, Daniel Henrique Barboza , qemu-devel@nongnu.org, muriloo@linux.ibm.com, dgilbert@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --asvhtkiiczUXV3OKguL80zXlPR2bRHJB0 From: Eric Blake To: Kevin Wolf Cc: Max Reitz , armbru@redhat.com, Daniel Henrique Barboza , qemu-devel@nongnu.org, muriloo@linux.ibm.com, dgilbert@redhat.com Message-ID: <56880d06-a214-2486-2e80-c565b33461b3@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 0/3] HMP/snapshot changes - do not use ID anymore References: <20180906111107.30684-1-danielhb413@gmail.com> <47023eb5-41f1-1b60-1094-d607999e93b6@redhat.com> <200ecea3-1ef4-3ecf-6b37-f6e45fef3849@redhat.com> <20190109172023.GK4867@localhost.localdomain> <40ef0a8d-3a25-4cc3-95f8-82bc4513776c@redhat.com> <20190109185154.GL4867@localhost.localdomain> In-Reply-To: <20190109185154.GL4867@localhost.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 1/9/19 12:51 PM, Kevin Wolf wrote: >> Indeed, and libvirt IS using 'savevm' via HMP via QMP's >> human-monitor-command, since there is no QMP counterpart for internal >> snapshot. Even though lately we consistently tell people that interna= l >> snapshots are underdeveloped and you should use external snapshots, it= >> does not get away from the fact that libvirt has been using 'savevm' t= o >> drive internal snapshots for years now, and that we MUST consider >> back-compat and/or add an introspectible QMP interface before making >> changes that would break libvirt. >=20 > Okay, so what does libvirt do when you request a snapshot with a > numerical name? Without having looked at the code, the best case I woul= d > expect that it forbids them, and more realistically I suspect that we > may actually fix a bug for libvirt by changing the semantics. >=20 > Or does libvirt really use snapshot IDs rather than names? At the moment, libvirt does not place any restriction on internal snapshot names, but passes the user's name through without thought of whether it is an id or a name. So yes, arguably tightening the semantics fixes a libvirt bug for libvirt having allowed internal snapshots to get into an inconsistent state. But again, it falls in the category of "properly fixing this requires a lot of auditing, time, mental power, and unit tests", which makes it a rather daunting task to state for certain. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --asvhtkiiczUXV3OKguL80zXlPR2bRHJB0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEY3OaSlgimHGqKqRv3g5py3orov0FAlw2RUoACgkQ3g5py3or ov3C4AgAioZffEAH/aiFtljvqh5Oculx7ddwOXjC7eSr5y1vy/UGOzHwscGMdsz7 HyGk8KjZzp+/w5sH0A3Ns+IRS7AUqAlSqOnhqeobTfNhxljyiL+BZR7BbXQwGING gO9VphOZ0DjTT7Ao/H/RjVpq+Z88pfaYmjxw2SBpzKad0wGpzGBBSEYl7Otd/y4C 9ajV/2mN7ld+IV47fFBAZOA3FPxM0MS0gAB5WMLr9HLb3IUKvYOv6dT+7payprqm m4HY0a9j1a6CLFTcmDitII+DWyjFfT0v/0ZoiZPMBweUKW3lIFYMfxHN9NxJQvLi ibuZU/dXoFnK4ftzkkOxYv1jkjYM1A== =FISw -----END PGP SIGNATURE----- --asvhtkiiczUXV3OKguL80zXlPR2bRHJB0--