From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:45576) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h3RPs-0003Iq-Vo for qemu-devel@nongnu.org; Mon, 11 Mar 2019 16:20:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h3RG5-0006Vb-Ad for qemu-devel@nongnu.org; Mon, 11 Mar 2019 16:10:50 -0400 References: <20190311165017.32247-1-kwolf@redhat.com> <20190311165017.32247-11-kwolf@redhat.com> <2f72f4e8-879a-62a5-d131-8c6562bd4043@redhat.com> <20190311195925.GA21327@angien.pipo.sk> From: Eric Blake Message-ID: <74cc34ed-a60b-75fd-3cf1-122ba485917e@redhat.com> Date: Mon, 11 Mar 2019 15:10:36 -0500 MIME-Version: 1.0 In-Reply-To: <20190311195925.GA21327@angien.pipo.sk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="HS3laJ3mheCE4nyOFQObwxRNqzfpfbYXz" Subject: Re: [Qemu-devel] [PATCH v2 10/10] file-posix: Make auto-read-only dynamic List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Krempa Cc: Kevin Wolf , qemu-block@nongnu.org, mreitz@redhat.com, berto@igalia.com, qemu-devel@nongnu.org, "stefanha@redhat.com" , Markus Armbruster This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --HS3laJ3mheCE4nyOFQObwxRNqzfpfbYXz From: Eric Blake To: Peter Krempa Cc: Kevin Wolf , qemu-block@nongnu.org, mreitz@redhat.com, berto@igalia.com, qemu-devel@nongnu.org, "stefanha@redhat.com" , Markus Armbruster Message-ID: <74cc34ed-a60b-75fd-3cf1-122ba485917e@redhat.com> Subject: Re: [PATCH v2 10/10] file-posix: Make auto-read-only dynamic References: <20190311165017.32247-1-kwolf@redhat.com> <20190311165017.32247-11-kwolf@redhat.com> <2f72f4e8-879a-62a5-d131-8c6562bd4043@redhat.com> <20190311195925.GA21327@angien.pipo.sk> In-Reply-To: <20190311195925.GA21327@angien.pipo.sk> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 3/11/19 2:59 PM, Peter Krempa wrote: >> auto-read-only was introduced in 3.1, at which point we intentionally >> had sufficiently loose wording to permit (but not require) dynamic sta= te >> checking; so you are not breaking the interface. On the other hand, i= s >> libvirt going to have problems introspecting whether it can use >> auto-read-only and get the dynamic behavior it needs? Or is there >> enough else in the way of libvirt's switch to -blockdev that it won't >> attempt anything that needs auto-read-only without other 4.0 interface= s >> anyway, at which point detecting the presence of the field (but not >> whether the field has a guarantee of dynamic behavior) on 3.1 doesn't >> matter? >=20 > I think we can use Stefan's capability detection mechanism he introduce= d > for the migration with cache enabled for local files to add a flag for > this as well. Except I thought we decided that the most recent version of his QMP changes was now fully-introspectible, thanks to using conditional compilation. https://lists.gnu.org/archive/html/qemu-devel/2019-03/msg02510.html Well, that may prove to be a short-lived hiatus, if libvirt would happily attempt to use qemu 3.1 and fail without some other introspectible hook to know whether auto-read-only has required semantics= =2E --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --HS3laJ3mheCE4nyOFQObwxRNqzfpfbYXz Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlyGwLwACgkQp6FrSiUn Q2oAyQgAoRF6PpnHx8Bo6NwrtDbeC724VlXsDN/wLSr2KtUjFaO5+AWSAB0RGSle GHI/kYSbBwijhk2rlWIe0lF0K1sI/P/h1SOVgAsOHL+FvPLuzu8nSP6dYjQL+ndy OQh/4tTkKtI+OOPmu/yWG5533kk2AMAh7LW0MggZxWlUBh/HvIMuPxJB8mb+jNpd o0rkm9Wjyj8+j60gRwiWTvoJJyVzkT9ApjvW9pfF4QOMQosdJxF3Kcu2/Zg08Sgw cL1odpvGAmo4jOltpaO4dU99KgID1tATOyavUf0KZHbFAqeI8YrNJBUax8KsnePl tEokHT5IKnfiw93GJ/hYbp3j4COXtQ== =+rT+ -----END PGP SIGNATURE----- --HS3laJ3mheCE4nyOFQObwxRNqzfpfbYXz--