Re: [Qemu-devel] [PATCH 1/3] qga: introduce guest-get-vcpus / guest-set-vcpus with stubs

[Laszlo Ersek]

On 03/06/13 14:49, Eric Blake wrote:
> On 03/05/2013 04:05 PM, Laszlo Ersek wrote:
>>>> +# If part or whole of the requested operation can't be carried out, the 
>>>> guest
>>>> +# VCPU state will be unspecified.
>>>
>>> Completely unspecified?
>>
>> Yes. "Unspecified" means "valid" (ie. at least one VCPU will be online,
>> the guest won't be "dead"), but no further info will be returned at once.
> 
> Hmm, just thinking aloud here (not saying we need to swap interfaces,
> unless you like this alternative):
> 
> What if we have guest-set-vcpus return a non-negative integer on
> success; namely, the number of consecutive array actions that were
> completed, and guarantee successful exit on first failure if any prior
> element was acted on?  Passing an empty array, or failing on the first
> array element, would give an error; otherwise, the error is lost if a
> user batches commands, but they would know how much of the batch failed,
> and can retry the command with the failing entry first to see what the
> failure was (assuming the failure is reproducible).  Basically, this
> would make guest-set-vcpus do partial write detection somewhat like write().

You can sell me anything POSIX :)

Thanks!
Laszlo