powerpc/mm/64: Document the sizes of/sizes mapped by Pxx_INDEX_SIZE

[Michael Ellerman]

On Thu, 2019-03-14 at 12:54:53 UTC, Michael Ellerman wrote:
> Add comments describing the size in bytes of the various levels of the
> page table tree, and the size of the virtual address space mapped by
> each level, to make it clear what the sizes are without having to also
> look up other definitions.
> 
> The code that calculates the sizes actually uses sizeof(pgd_t) etc.,
> so in theory these comments could skew vs the code, but the size of
> pgd_t etc. is unlikely to change very often.
> 
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>

Applied to powerpc next.

https://git.kernel.org/powerpc/c/eea86aa4171d4960f0fcdc99dab358c2

cheers