From: Markus Armbruster <armbru@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: "Denis Plotnikov" <dplotnikov@virtuozzo.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org,
"Max Reitz" <mreitz@redhat.com>
Subject: Re: ImageInfo oddities regarding compression
Date: Fri, 27 Nov 2020 17:52:09 +0100 [thread overview]
Message-ID: <87eeken3nq.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <20201127152534.GC4736@merkur.fritz.box> (Kevin Wolf's message of "Fri, 27 Nov 2020 16:25:34 +0100")
Kevin Wolf <kwolf@redhat.com> writes:
> Am 27.11.2020 um 13:21 hat Markus Armbruster geschrieben:
>> >> I fell down this (thankfully shallow) rabbit hole because we also have
>> >>
>> >> { 'enum': 'MultiFDCompression',
>> >> 'data': [ 'none', 'zlib',
>> >> { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] }
>> >>
>> >> I wonder whether we could merge them into a common type.
>>
>> Looks like we could: current code would never report the additional
>> value 'none'. Introspection would show it, though. Seems unlikely to
>> cause trouble. Observation, not demand.
>
> Forgot to comment on this one...
>
> Technically we could probably, but would it make sense? Support for
> compression formats has to be implemented separately for both cases, so
> that they currently happen to support the same list is more of a
> coincidence.
>
> If we ever add a third compression format to qcow2, would we add the
> same format to migration, too, or would we split the schema into two
> types again?
I figure if a compression method is worth adding to one, it's probably
worth adding to the other.
Having two separate enums isn't too bad. A third has been proposed[*],
but I hope we can reuse migration's existing enum there.
[*] [PATCH 1/6] migration: Add multi-thread compress method
next prev parent reply other threads:[~2020-11-27 16:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 10:06 ImageInfo oddities regarding compression Markus Armbruster
2020-11-27 10:14 ` Daniel P. Berrangé
2020-11-27 10:32 ` Kevin Wolf
2020-11-27 12:21 ` Markus Armbruster
2020-11-27 15:25 ` Kevin Wolf
2020-11-27 16:52 ` Markus Armbruster [this message]
2020-11-30 17:36 ` Daniel P. Berrangé
2020-11-30 17:24 ` Eric Blake
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