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Wed, 11 Dec 2019 12:32:15 +0000 (UTC) Received: from redhat.com (ovpn-112-62.ams2.redhat.com [10.36.112.62]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 886AB1001B07; Wed, 11 Dec 2019 12:32:13 +0000 (UTC) Date: Wed, 11 Dec 2019 12:32:10 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Kevin Wolf Subject: Re: Insufficiently documented deprecated command arguments Message-ID: <20191211123210.GH955178@redhat.com> References: <87tv67wa9y.fsf@dusky.pond.sub.org> <20191211093317.GB2441258@angien.pipo.sk> <20191211101439.GA6505@linux.fritz.box> <20191211105147.GC2441258@angien.pipo.sk> <20191211122417.GB6505@linux.fritz.box> MIME-Version: 1.0 In-Reply-To: <20191211122417.GB6505@linux.fritz.box> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: Em5WSsJONDi5upzBJTWisQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Peter Krempa , Markus Armbruster , qemu-block@nongnu.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Dec 11, 2019 at 01:24:17PM +0100, Kevin Wolf wrote: > Am 11.12.2019 um 11:51 hat Peter Krempa geschrieben: > > On Wed, Dec 11, 2019 at 11:14:39 +0100, Kevin Wolf wrote: > > > Am 11.12.2019 um 10:33 hat Peter Krempa geschrieben: > > > > On Wed, Dec 11, 2019 at 09:12:41 +0100, Markus Armbruster wrote: > > > > > Commit 7a9877a026 "block: Accept device model name for > > > > > block_set_io_throttle" (v2.8.0) deprecated block_set_io_throt= tle > > > > > argument @device. > > > >=20 > > > > This one is more complex. The command is used both in 'blockdev' an= d in > > > > 'drive' mode: > > > >=20 > > > > In 'drive' mode we pass the alias of the 'drive' as the @device > > > > argument. > > > >=20 > > > > In 'blockdev' mode we pass the qom name as @id > > >=20 > > > Any reason you couldn't use the QOM name even in 'drive' mode for any > > > QEMU version that has the @id option? > >=20 > > Honestly, I didn't want to change the existing implementation at all. > >=20 > > If it will help I can change that as it will be pretty easy to do. >=20 > You can keep it for until after the blockdev dust has settled. It would > "just" be to address the deprecation since QEMU 2.8, not because of any > functional change. >=20 > > >=20 > > > > > Commit c42e8742f5 "block: Use JSON null instead of "" to disa= ble > > > > > backing file" (v2.10.0) deprecated blockdev-add empty string > > > > > argument @backing. > > > >=20 > > > > This is used in 'blockdev' mode only and we always pass the JSON nu= ll or > > > > a node name string. > > >=20 > > > Here the thing to consider might be that JSON null isn't easy to use = on > > > the command line for manual users. > > >=20 > > > > > These were missed in commit eb22aeca65 "docs: document deprec= ation > > > > > policy & deprecated features in appendix" (v2.10.0). > > > > >=20 > > > > > Commit 3c605f4074 "commit: Add top-node/base-node options" (v= 3.1.0) > > > > > deprecated block-commit arguments @base and @top. > > > >=20 > > > > This command also has two modes: > > > >=20 > > > > In 'drive' mode we pass in path strings as @base and @ top. > > > >=20 > > > > In 'blockdev' mode we pass in nodenames as @base-node and @top-node= . > > > >=20 > > > > Starting from qemu-4.2 libvirt uses 'blockdev' mode for VMs unless = an SD > > > > card is configured as we didn't convert to the '-device' approach f= or > > > > those as AFAIK not everything is possible to be converted. > > >=20 > > > Hm... I guess in 'drive' mode, you stil don't assign node names, so y= ou > > > actually have to rely on paths? > >=20 > > Well, in some specific cases we could detect the node names > > auto-assigned by qemu and use them instead of paths, but in my opinion > > it's not worth the effort and extra code. >=20 > Well, the question is what to do on the QEMU side then. Deprecation > should mean that we have a plan for removing the feature. If we're > planning to keep the feature indefinitely because libvirt needs it, we > might want to consider removing the deprecation notice. Ideally libvirt would stop using -drive entirely, as I hate the idea of having to keep this around indefinitely in libvirt too. This needs QEMU to close the last gaps wrt SD cards Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberrange= :| |: https://libvirt.org -o- https://fstop138.berrange.com= :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange= :|