Re: [RFC v5 01/38] powerpc: Free up four 64K PTE bits in 4K backed HPTE pages

On Wed, 2017-07-05 at 14:21 -0700, Ram Pai wrote:

Rearrange 64K PTE bits to  free  up  bits 3, 4, 5  and  6,
in the 4K backed HPTE pages.These bits continue to be used
for 64K backed HPTE pages in this patch, but will be freed
up in the next patch. The  bit  numbers are big-endian  as
defined in the ISA3.0

The patch does the following change to the 4k htpe backed
64K PTE's format.

The diagrams make the patch much easier to understand, thanks!

<snip>
 

NOTE:even though bits 3, 4, 5, 6, 7 are  not  used  when
the  64K  PTE is backed by 4k HPTE,  they continue to be
used  if  the  PTE  gets  backed  by 64k HPTE.  The next
patch will decouple that aswell, and truely  release the
bits.

<snip>

Balbir Singh.