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

[Jan Kiszka]

Markus Armbruster wrote:
> Avi Kivity <address@hidden> writes:
> 
>> On 05/23/2010 10:57 AM, Jan Kiszka wrote:
>>> Avi Kivity wrote:
>>>    
>>>> On 05/22/2010 11:18 AM, Jan Kiszka wrote:
>>>>      
>>>>> From: Jan Kiszka<address@hidden>
>>>>>
>>>>> This introduces device_show, a monitor command that saves the vmstate of
>>>>> a qdev device and visualizes it. QMP is also supported. Buffers are cut
>>>>> after 16 byte by default, but the full content can be requested via
>>>>> '-f'. To pretty-print sub-arrays, vmstate is extended to store the start
>>>>> index name. A new qerror is introduced to signal a missing vmstate. And
>>>>> it comes with documentation.
>>>>>
>>>>> +
>>>>> +Dump a snapshot of the device state. Buffers are cut after 16 bytes
>>>>> unless
>>>>> +a full dump is requested.
>>>>> +
>>>>> +Arguments:
>>>>> +
>>>>> +- "path": the device's qtree path or unique ID (json-string)
>>>>>
>>>>>        
>>>> This may be ambiguous.
>>>>      
>>> Can your elaborate what precisely is ambiguous?
>>>    
>> Can't the user choose the unique ID so that it aliases an unrelated
>> qtree path?
>>
>> I prefer having mutually exclusive 'path' and 'ref' arguments.
> 
> Don't think that's necessary.  If the string starts with '/', it's an
> absolute path.  Else, it's a relative path rooted at the node with the
> ID equal to the first component.

'pci.0' can be both a (badly chosen) ID as well as an abbreviated qtree
path.

> 
> Currently breaks down when IDs contain '/', but permitting that is a
> bug.  There may be more problems; the path lookup code is way too
> clever.

Indeed. Less can sometimes be more. My impression is that some of the
cleverness was motivated by lacking qtree completion for the HMP.

Jan

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