From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52970) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XqbXy-0000LP-9u for qemu-devel@nongnu.org; Tue, 18 Nov 2014 00:41:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XqbXx-0005c0-2L for qemu-devel@nongnu.org; Tue, 18 Nov 2014 00:41:50 -0500 Received: from ozlabs.org ([2401:3900:2:1::2]:57662) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XqbXw-0005bL-OF for qemu-devel@nongnu.org; Tue, 18 Nov 2014 00:41:49 -0500 Date: Tue, 18 Nov 2014 15:34:52 +1100 From: David Gibson Message-ID: <20141118043452.GD2867@voom.redhat.com> References: <1412358473-31398-1-git-send-email-dgilbert@redhat.com> <1412358473-31398-11-git-send-email-dgilbert@redhat.com> <20141103030550.GF8949@voom.redhat.com> <20141103190447.GE29967@work-vm> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="AbQceqfdZEv+FvjW" Content-Disposition: inline In-Reply-To: <20141103190447.GE29967@work-vm> Subject: Re: [Qemu-devel] [PATCH v4 10/47] Return path: Open a return path on QEMUFile for sockets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, cristian.klein@cs.umu.se, qemu-devel@nongnu.org, amit.shah@redhat.com, yanghy@cn.fujitsu.com --AbQceqfdZEv+FvjW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 03, 2014 at 07:04:48PM +0000, Dr. David Alan Gilbert wrote: > * David Gibson (david@gibson.dropbear.id.au) wrote: > > On Fri, Oct 03, 2014 at 06:47:16PM +0100, Dr. David Alan Gilbert (git) = wrote: > > > From: "Dr. David Alan Gilbert" > > >=20 > > > Postcopy needs a method to send messages from the destination back to > > > the source, this is the 'return path'. > > >=20 > > > Wire it up for 'socket' QEMUFile's using a dup'd fd. > >=20 > > This doesn't seem like the right abstraction to me. In particular I > > can't really see how you'd implement this for anything other than > > socket. > >=20 > > I'd suggest instead creating new "open" helper functions (within the > > QEMUFile code) that open both a forward and return path > > simultaneously. >=20 > Can you give an example of a transport where it would be a problem, > so I can look at how that works? pipe socket routed through some external transport / encoding layer that's one way only. > It's a little tricky since, on the destination, at the time we create > the connection we don't know that we're going to need the return path. Creating it and not using it shouldn't be a problem though, should it? As long as you just fall back to precopy rather than failing the migration if you're unable to open it. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --AbQceqfdZEv+FvjW Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUasxsAAoJEGw4ysog2bOSujEP/2vTDav1jIgyv8g3d3K8+wfS KbBUqcHriylNQ6sKed30IgXaYOpfrArAziWAgCkLWCgh4ZUILBe85MY3kBBFrnju 6rJzikHXwryRpEiNga9bDJFipocyYrvhfr+TZTkLHbwhmSJzLFfk9NSLOP8hGbq9 S1FFvHxuyvoHgHrDBfBp+TC3FMEBo0VtWbCCTya+PrtFtpvFzyycvatFBfa6+jUW o9fKeMbn3iGIo0wJSCyfLa7WVZMlLmXW71Q0ALUKizQzIaJ8Zr0jUz6iSqWfyTBQ wEp2nZqOI1k425HOVdwla6fCyk4YrA63a+UTvGkP0n3jYsTNWJeu1q4HlY8KAsU+ 77AdUaBg9pzWvLJy2Q4ut3QDMzzvgh6FxOo2ZUjF2ZfLsQ00mJEKZ1ykQCSw9WBi 86hfOUKLwi7IJWp55b2MPOJ/JoSNkF2W3KmBhC+PLEyixEF4GK7+nt3kmcawYhtD 7bK3fPF2YLhcg+6oNZtWkVD28+Ks5P2cs/A+eTDjYSO5Xdd0068o0Gpom/eRLTva xKLE1P3vKj9kxPiuEvTTGopHGhwjmLiVrGGpOZSH5u+Kt2uw0AIcsZn5oo8RVFz0 exFDETY4ju8oFVCR2+Ajfm4aVxkPnfNXh/CgGznmvkvgc2R4Wgg7nQRQw4P7DbaG OtcE5eE/4u3LgThqH7H9 =517n -----END PGP SIGNATURE----- --AbQceqfdZEv+FvjW--