Re: [Xen-devel] [PATCH v2 16/30] x86/cpu: Move set_cpumask() calls into c_early_init()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 17/02/16 10:58, Jan Beulich wrote:
>>>> On 17.02.16 at 11:45, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 16/02/16 14:10, Jan Beulich wrote:
>>>>>> On 05.02.16 at 14:42, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> Before c/s 44e24f8567 "x86: don't call generic_identify() redundantly", the
>>>> commandline-provided masks would take effect in Xen's view of the features.
>>>>
>>>> As the masks got applied after the query for features, the redundant call 
>>>> to
>>>> generic_identify() would clobber the pre-masking feature information with 
>>>> the
>>>> post-masking information.
>>>>
>>>> Move the set_cpumask() calls into c_early_init() so their effects take 
>>>> place
>>>> before the main query for features in generic_identify().
>>>>
>>>> The cpuid_mask_* command line parameters now limit the entire system, a
>>>> feature XenServer was relying on for testing purposes.
>>> And I continue to view this as a step backwards, and hence can't
>>> really approve of this change.
>> It is not a step backwards.  Being able to disable features in Xen is
>> critical for testing.  You accidentally broke that with a patch which
>> was supposed to be no functional change.
> Views differ: I would say I unknowingly fixed this with that patch
> (as to me it was always clear that this masking should not apply to
> Xen itself).
>
> If that behavior is critical for testing, add a command line option
> to enable it.

This series returns the command line options to their original
behaviour, and avoids them needing to be used for levelling. 
Introducing yet another command line option would be pointless.

~Andrew

>
>> This series means that these command line options are not required for
>> levelling.
> By the end of the series, agreed.
>
> Jan
>


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