Re: [Qemu-devel] Re: [PATCH v2 12/15] monitor: Add basic device state visualization

[Jan Kiszka <jan.kiszka@web.de>]

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Anthony Liguori wrote:
> On 05/24/2010 03:35 PM, Jan Kiszka wrote:
>> In contrast to save/loadvm, device_show does not provide a
>> backward-compatible output. Not only field names can change (as a result
>> of internal refactoring),
> 
> Field names could change, but that seems unlikely and unnecessary.

Actually, this may happen to improve the output format for device_show,
either via renaming the fields or annotating it (once we have the latter
mechanism).

> 
>>   fields may even disappear,
> 
> That would break live migration. 

Nope. We can (and I think we did before) perfectly read some field up to
version X and convert it into the new format but skip that field for X+1
upward.

> The output of device_show when
> specifying -M pc-0.13 should always be the same.  If it's not, I believe
> that's a bug.
> 
> The output of device_show across multiple qemu versions without
> specifying a -M could certainly be different but that's to be expected
> since you have a different hardware model.

It will be different as soon as the version_id of a dumped vmstate
changes, even independent of -M.

Jan


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