From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55835) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aBert-0007ai-Bn for qemu-devel@nongnu.org; Wed, 23 Dec 2015 03:33:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aBers-00041E-Iv for qemu-devel@nongnu.org; Wed, 23 Dec 2015 03:33:57 -0500 Date: Wed, 23 Dec 2015 16:33:43 +0800 From: Stefan Hajnoczi Message-ID: <20151223083343.GB8461@stefanha-x1.localdomain> References: <87vb7vc2yt.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="aVD9QWMuhilNxW9f" Content-Disposition: inline In-Reply-To: <87vb7vc2yt.fsf@blackfin.pond.sub.org> Subject: Re: [Qemu-devel] Minutes from the "Stuttgart block Gipfele" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: Kevin Wolf , Fam Zheng , qemu-block@nongnu.org, Jeff Cody , qemu-devel@nongnu.org, Max Reitz , Alberto Garcia , John Snow --aVD9QWMuhilNxW9f Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Dec 18, 2015 at 02:15:38PM +0100, Markus Armbruster wrote: > What should happen when the user asks for a mutation at a place where we > have implicit filter(s)? Please suspend your disbelief for a second: In principle it's simplest not having implicit filters. The client needs to set up throttling nodes or the backup filter explicitly. Okay, now it's time to tear this apart: For backwards compatibility it's necessary to support throttling, copy-on-read, backup notifier, etc. It may be possible to tag implicit filter nodes so that mutation operations that wouldn't be possible today are rejected. The client must use the explicit syntax to do mutations on implicit filters. This is easier said than done, I'm not sure it can be implemented cleanly. Another problem is that the backup block job and other operations that require a single command today could require sequences of low-level setup commands to create filter nodes. The QMP client would need to first create a write notifier filter and then start the backup block job with the write notifier node name. It's clumsy. Stefan --aVD9QWMuhilNxW9f Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJWelxnAAoJEJykq7OBq3PIWacH/3aiZE+XF5wdMMFOiivKBwCM 5qr55cXh7EGbHRzQzxL+X96Pj1DMwTbmPRabtmotPmiCugYiDQFF6Z3rGPkHvi14 cyZgyKKpNakWp+yZ2xpNKCmtjWE588iGAp9GsMaMDvSVC0mJq0+WTjHITGHWUQWH 1p5LVu8kjh6dE4TCVQRIvGRhHdcOSmvPf8kUPHB1hrLVXnWQCnlqcN1bFUVz/nzH eXYtNLF3zAwTT6AuaRHRv/Qp+2B6RpK0dGzaB5hqEzUeKOE3i8NV1AZIkQlObbl3 WjwPEqRd393MhvhWWesRckAsHGKiv5jCrBfZ+ktElP2uNOtNMPb8cwv8PGBeiTI= =wOeW -----END PGP SIGNATURE----- --aVD9QWMuhilNxW9f--