[PATCH for-4.8 02/10] powerpc/mm: Convert early cpu/mmu feature check to use the new helpers

[Aneesh Kumar K.V]

Benjamin Herrenschmidt <benh at kernel.crashing.org> writes:

> On Wed, 2016-07-13 at 15:08 +0530, Aneesh Kumar K.V wrote:
>> This switch most of the early feature check to use the non static key
>> variant of the function. In later patches we will be switching
>> cpu_has_feature and mmu_has_feature to use static keys and we can use
>> them only after static key/jump label is initialized. Any check for
>> feature before jump label init should be done using this new helper.
>
> I'm not sure about that. This is converting way way way way more
> functions than is needed. Especially if Michael applies my series
> there will be very little code run before the patching, really only the
> MMU initialization....
>

But then all of them are __init functions and that help in:

1) Avoid adding those location information to the __jump_table section. (I assume
that will also have an impact of vmlinux size ?)
2) Simple rule regarding when to use __cpu_has_feature and
cpu_has_feature
3) No need to runtime patch lot of these __init code paths which will we
throw out after boot.

Do you see any draw back in making all the __init functions to use
__cpu_has_feature() ?

-aneesh