Re: [PATCH v3 08/13] libs/guest: make a cpu policy compatible with older Xen versions

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.05.2021 12:23, Roger Pau Monné wrote:
> On Wed, May 05, 2021 at 09:42:09AM +0200, Jan Beulich wrote:
>> On 04.05.2021 17:34, Roger Pau Monné wrote:
>>> On Mon, May 03, 2021 at 01:09:41PM +0200, Jan Beulich wrote:
>>>> On 30.04.2021 17:52, Roger Pau Monne wrote:
>>>>> @@ -1086,3 +1075,42 @@ int xc_cpu_policy_calc_compatible(xc_interface 
>>>>> *xch,
>>>>>  
>>>>>      return rc;
>>>>>  }
>>>>> +
>>>>> +int xc_cpu_policy_make_compatible(xc_interface *xch, xc_cpu_policy_t 
>>>>> policy,
>>>>> +                                  bool hvm)
>>>>
>>>> I'm concerned of the naming, and in particular the two very different
>>>> meanings of "compatible" for xc_cpu_policy_calc_compatible() and this
>>>> new one. I'm afraid I don't have a good suggestion though, short of
>>>> making the name even longer and inserting "backwards".
>>>
>>> Would xc_cpu_policy_make_compat_412 be acceptable?
>>>
>>> That's the more concise one I can think of.
>>
>> Hmm, maybe (perhaps with an underscore inserted between 4 and 12). Yet
>> (sorry) a comment in the function says "since Xen 4.13", which includes
>> changes that have happened later. Therefore it's not really clear to me
>> whether the function really _only_ deals with the 4.12 / 4.13 boundary.
> 
> It should deal with any changes in the default cpuid policy that
> happened after (and not including) Xen 4.12. So resulting policy is
> compatible with the behaviour that Xen 4.12 had. Any changes made in
> Xen 4.13 and further versions should be accounted for here.

I see.

Jan