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Re: [Qemu-devel] QMP, HMP: introduce 'writeconfig' command
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] QMP, HMP: introduce 'writeconfig' command |
Date: |
Tue, 24 Oct 2017 11:45:53 +0100 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
* Vadim Galitsyn (address@hidden) wrote:
> Hi Guys,
>
> This thread is a continuation of discussion started in
> http://lists.nongnu.org/archive/html/qemu-devel/2017-02/msg03182.html.
>
> This series introduces ‘writeconfig’ command support for QMP and HMP
> monitors. This functionality might be useful for live migration for cases
> when guest configuration was modified in runtime (for example as a result of
> hot- plug/unplug operations) and actual Qemu command line no longer reflects
> setup exposed to guest.
>
> Original series has ‘qemu_opts’ patch as well
> (http://lists.nongnu.org/archive/html/qemu-devel/2017-02/msg03183.html)
> because HMP’s ‘object_add’ result was not reflected in ‘writeconfig’ output.
> Later I found that QMP’s ‘object-add’ has the same issue. Anyway, I don’t
> include ‘qemu_opts’ patches here because Markus mentioned (here
> http://lists.nongnu.org/archive/html/qemu-devel/2017-02/msg03476.html) that
> this functionality is going to be reworked in some future and such patches
> might collide with the rework process.
>
> Markus, could you please post if you have an update on this topic? Current
> ‘master’ branch (9993c82dc2f5ce58b41d708b765e1a717ad4281d) still has the
> issue.
>
> Also, Markus mentioned that once configuration was changed during live
> migration -- it might be an issue because ‘writeconfig’ data became outdated
> (and might be make sense to think about to embed this data into migration
> stream itself). In the same time David said that this is another problem
> which is unrelated to this patch series. What is your current opinion on this
> topic? Can we consider these patches to be included into ‘master’ taking into
> account that not all configuration is dumped by ‘writeconfig’ (‘object_add’
> problem), but this can be fixed later?
I don't see anything wrong with having a 'writeconfig' command - we
already have the command line equivalent - that is assuming hotplug
etc all cause the values written to be correct.
The data becoming outdated doesn't sound like a big issue to me;
it's the management layer that's doing any hotplugs, it can reissue
another 'writeconfig' command.
Dave
>
> Best regards,
> Vadim
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH 1/4] qmp: introduce 'writeconfig' command, (continued)
- [Qemu-devel] [PATCH 1/4] qmp: introduce 'writeconfig' command, Vadim Galitsyn, 2017/10/23
- [Qemu-devel] [PATCH 2/4] hmp: introduce 'writeconfig' command, Vadim Galitsyn, 2017/10/23
- [Qemu-devel] [PATCH 3/4] tests: test-hmp: extend with 'writeconfig' command, Vadim Galitsyn, 2017/10/23
- [Qemu-devel] [PATCH 4/4] tests: test-hmp: print command execution result, Vadim Galitsyn, 2017/10/23
- Re: [Qemu-devel] QMP, HMP: introduce 'writeconfig' command,
Dr. David Alan Gilbert <=