[libvirt] [PATCH] docs: formatdomain: Clarify CPU feature policy option "require"

[John Ferlan]

On 03/30/2018 06:21 AM, Kashyap Chamarthy wrote:
> On Thu, Mar 29, 2018 at 12:22:18PM -0400, John Ferlan wrote:
>>
>>
>> On 03/26/2018 06:53 AM, Kashyap Chamarthy wrote:
>>> (Thanks: Jiri Denemark, for clarifying this on IRC.)
>>
>> Lost context here!  That should have gone under the --- cause it'll look
>> awfully strange in git history.
> 
> Yeah, indeed.  Sorry, it should've gone under the "---".
> 
> So the clarification that Jiri gave was about the 'require' value for
> 'policy' attribute for a CPU feature.  In this context, 'require'
> actually means that the guest CPU will have the said feature so that the
> host CPU does not need to support it -- if QEMU can emulate it.
> 
> E.g. 'x2apic' is emulated by QEMU even if the host does not support it:
> 
>     <feature policy='require' name='x2apic'/>
> 
>> Is there "more" or "extra" text you'd like to see added?  Or is the
>> commit message good enough?  
> 
> I wanted to add more clarification, like above.  Can Jiri or anyone
> cross-verify what I said above is correct?
> 

So if I change to:

Using the 'require' value for the 'policy' attribute indicates
that the guest will have the feature so the host CPU does not need
to support it if the hypervisor can emulate it.

E.g. 'x2apic' is emulated by QEMU even if the host does not support it:

    <feature policy='require' name='x2apic'/>


I think that covers it.

John

>> I can add before pushing so you don't need
>> to spin another version...
> 
> Thanks a lot!
> 
>>>
>>> Signed-off-by: Kashyap Chamarthy <kchamart at redhat.com>
>>> ---
>>>  docs/formatdomain.html.in | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
>>> index 6fd2189cd..2410c92af 100644
>>> --- a/docs/formatdomain.html.in
>>> +++ b/docs/formatdomain.html.in
>>> @@ -1532,7 +1532,7 @@
>>>              of it being supported by host CPU.</dd>
>>>            <dt><code>require</code></dt>
>>>            <dd>Guest creation will fail unless the feature is supported by host
>>> -            CPU.</dd>
>>> +            CPU or the hypervisor is able to emulate it".</dd>
>>                                                           ^
>> I'll also remove the random "
> 
> Oops.  Thanks!
> 
>> Reviewed-by: John Ferlan <jferlan at redhat.com>
>>
>> John
>>
>> (should be safe for freeze too, but I won't push until my commit message
>> question is answered).
>>
>>>            <dt><code>optional</code></dt>
>>>            <dd>The feature will be supported by virtual CPU if and only if it
>>>              is supported by host CPU.</dd>
>>>
>