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SubjectRe: [PATCH] x86: pat cpu feature bit setting for known cpus
Ingo Molnar wrote:
> * Venki Pallipadi <venkatesh.pallipadi@intel.com> wrote:
>
>>>> OK, note previous question: what is the motivation for having
>>>> this as a whitelist (as opposed to a blacklist)?
>>> Venkatesh could tell?
>> Main reason for white-list at this point is not to be side-tracked by
>> real or potential erratas on older CPUs. Focussing on getting the
>> support for this feature on current and future CPUs. If older CPUs
>> have survived all these days without this feature, they should be
>> doing OK.
>
> well, the upside would be that since most testing of Linux kernels is
> done on _old_ hardware (people tend to risk their old hw first ;-), we'd
> get faster convergence of the codebase, even though we have the risk of
> erratas (known and unknown ones alike). Code that artificially limits
> its utility is almost always slow to stabilize.
>

Yes, using a whitelist of this type is wrong, IMO, and smells faintly of
vendor-lockin.

-hpa


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