Re: [Qemu-devel] [PATCH 0/3] Fix confused output for alias properties

[Eric Blake <eblake@redhat.com>]

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On 09/16/2014 11:54 PM, Markus Armbruster wrote:
> Eric Blake <eblake@redhat.com> writes:
> 
>> On 09/16/2014 12:31 PM, Paolo Bonzini wrote:
>>
>>>> Change legacy_name to point to a detailed human-readable
>>>> description of the type?
>>>> E.g. "Ethernet 6-byte MAC Address, format: AA:BB:CC:DD:EE:FF"?
>>>
>>> If libvirt can cope with
>>>
>>> e1000.mac=str (Ethernet 6-byte MAC Address, format: AA:BB:CC:DD:EE:FF)
>>
>> Isn't this output only available under -help? Libvirt only cares about
>> QMP listings of devices and their properties, so improving the human
>> interface should have no negative impact to the machine interface.
> 
> Libvirt still has code parsing this, see virQEMUCapsExtractDeviceStr().
> Whether it's actually used with recent QEMU I don't know.

That code is only used for qemu < 1.5 (when -help parsing is all we can
use) - but those versions of qemu are not going to change -help output,
and new versions of qemu use only QMP, so you are free to change it with
no impact to libvirt.

> 
> -device FOO,help merely formats qmp_device_list_properties()'s value for
> human consumption.  So, to make a description string available for help,
> we also have to put it into the function's value.  If we don't want it
> in QMP, we need to filter it out in the command handler.  Right now,
> qmp_device_list_properties() *is* the command handler.
> 
> Aside: why isn't the QMP command named query-device-list-properties?  We
> suck at consistency!
> 
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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