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Re: proposal: deprecate -readconfig/-writeconfig
From: |
Markus Armbruster |
Subject: |
Re: proposal: deprecate -readconfig/-writeconfig |
Date: |
Fri, 15 May 2020 07:54:27 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) |
Paolo Bonzini <address@hidden> writes:
> On 14/05/20 10:56, Daniel P. Berrangé wrote:
>> On Thu, May 14, 2020 at 10:09:21AM +0200, Paolo Bonzini wrote:
>>> IMHO configuration files are in general a failed experiment. In
>>> practice, they do not add much value over just a shell script because
>>> they don't allow configuring all QEMU options, they are very much fixed
>>> (by their nature). I think it's more or less agreed that they are not
>>> solving any problem for higher-level management stacks as well; those
>>> would prefer to configure the VM via QMP or another API.
>>>
>>> So, any objections to deprecating -readconfig and -writeconfig?
>>
>> Libvirt would like to have a config file for QEMU, but it would have
>> to be one that actually covers all the config options QEMU supports,
>> and ideally using a data format in common with that used for runtime
>> changes. So for libvirt's needs the current readconfig is entirely
>> useless.
>
> Yes, this is what I was thinking about.
>
>> For a less general purpose mgmt app, that targets some specific use
>> cases I could imagine people might have used readconfig. [...]
>> If we deprecate them, the only alternative users have right now is
>> to go back to passing CLI args. [...] We'd be deciding to kill the
>> feature with no direct replacement, even though it is potentially
>> useful in some limited scenarios.
>>
>> If we have a general strategy to eliminate QemuOpts and move entirely
>> to QAPI based config, then I can see -readcofig/-writeconfig may be
>> creating a burden of back compatibility on maintainers.
>
> I don't see QemuOpts going away anytime soon, but I do see more QMP/QAPI
> and less command line in the future as far as management tools are
> concerned. QemuOpts and HMP will remain for direct usage, for the
> foreseeable future.
I'd prefer not to have two separate configuration infrastructures.
> So I guess we can keep -readconfig but deprecate, or even remove,
> -writeconfig.
Deprecate both as stable interfaces, remove neither.