From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:54179) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1Vur-00013C-DY for qemu-devel@nongnu.org; Wed, 06 Mar 2019 07:44:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h1Vup-0007q1-5Z for qemu-devel@nongnu.org; Wed, 06 Mar 2019 07:44:57 -0500 References: <20190301160929.19892-1-stefanha@redhat.com> <20190306101811.GJ22159@stefanha-x1.localdomain> From: Eric Blake Message-ID: <1aab9bb5-a8a1-b0c8-af6f-909631e9ce2f@redhat.com> Date: Wed, 6 Mar 2019 06:44:42 -0600 MIME-Version: 1.0 In-Reply-To: <20190306101811.GJ22159@stefanha-x1.localdomain> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FhYRnWoFjMG8OVsB5T1FupPuAwnb93Ohi" Subject: Re: [Qemu-devel] [PATCH v2] file-posix: add drop-cache=on|off option List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, Kevin Wolf , qemu-block@nongnu.org, Markus Armbruster , Neil Skrypuch , Max Reitz , Stefano Garzarella This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --FhYRnWoFjMG8OVsB5T1FupPuAwnb93Ohi From: Eric Blake To: Stefan Hajnoczi Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, Kevin Wolf , qemu-block@nongnu.org, Markus Armbruster , Neil Skrypuch , Max Reitz , Stefano Garzarella Message-ID: <1aab9bb5-a8a1-b0c8-af6f-909631e9ce2f@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] file-posix: add drop-cache=on|off option References: <20190301160929.19892-1-stefanha@redhat.com> <20190306101811.GJ22159@stefanha-x1.localdomain> In-Reply-To: <20190306101811.GJ22159@stefanha-x1.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 3/6/19 4:18 AM, Stefan Hajnoczi wrote: >> Question - if we used qapi's 'if':COND to only declare the field on >> platforms where we know at compile time that we can support it, would >> that be enough for libvirt to introspect that if the field exists then= >> migration is safe, without having to rely on an query-qemu-features co= mmand? >=20 > Yes, although this raises another question: >=20 > The drop-cache implementation is not #ifdefed in file-posix.c. If we > make the QMP schema conditional, should we also #ifdef the command-line= > option in raw_runtime_opts[] to prevent QEMU from silently ignoring thi= s > option? Yes, that would make sense to me - if we don't advertise the feature, then we should not silently ignore it on the command line. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --FhYRnWoFjMG8OVsB5T1FupPuAwnb93Ohi Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlx/wLoACgkQp6FrSiUn Q2qM6Af/XuaPPEH1lPsett6iLP0z247rNLOisLguFVLxKUlm0G/WMcm9Z65j00Zk mQf9P1/0o//lM8e0Dg94zxGKZciV4PLoFVb0a9iGh0FC8Q7h9RtJPNofM65OxXp8 3Y0/GoSa8f/KLvrZsd/iDoak1UfVw8mJ/ggGfxUiYQVFIbdlFbxJ8DqV0JJA2OJo uIwbJm2mYQn9nD9QZJtSnj82f/aqbtCOpnfZix4Cwn5FvJoMDHtPbgkFTdsbVran KI7z1P2vNUW2ROtT0nD7pTWuwdCCWxUC4/nzBUGezrVkAU2qisnC5u5ex8WHXhS0 Bpr3i9CD3FUg+9RQEC4h63n+jzzHhg== =7zEn -----END PGP SIGNATURE----- --FhYRnWoFjMG8OVsB5T1FupPuAwnb93Ohi--