Re: [PATCH V4 00/18] Book3s abstraction in preparation for new MMU model

On Tue, 2016-02-23 at 14:56 +0530, Aneesh Kumar K.V wrote:

"Aneesh Kumar K.V" [off-list ref] writes:

quoted

Hello,

This series mostly consisting of code movement. One new thing added in
this series
is to switch book3s 64 to 4 level page table. The changes are done to
accomodate
the upcoming new memory model in future powerpc chips. The details of the
new
MMU model can be found at

 http://ibm.biz/power-isa3 (Needs registration). I am including a summary
of the changes below.

ISA 3.0 adds support for the radix tree style of MMU with full
virtualization and related control mechanisms that manage its
coexistence with the HPT. Radix-using operating systems will
manage their own translation tables instead of relying on hcalls.

Radix style MMU model requires us to do a 4 level page table
with 64K and 4K page size. The table index size different page size
is listed below

PGD -> 13 bits
PUD -> 9 (1G hugepage)
PMD -> 9 (2M huge page)
PTE -> 5 (for 64k), 9 (for 4k)

We also require the page table to be in big endian format.

Changes from V3:
 * rebase on top of PTE bits movement patch series
 * Drop all the hash linux abstraction patches
 * Keep only 4 level table and other code movement patches.

Changes from V2:
 * rebase to latest kernel
 * Update commit messages
 * address review comments

Changes from V1:
* move patches adding helpers to the next series


NOTE:
 This is lightly tested. Right now 4K linux page size is what is being
tested. Once that is done
 I will have to do 64K linux page size tests.

Tested the below tests with 4K page size and 64K page size
* libhugetlbfs test
* ltp mm tests
* kernel build in loop (testing thp collapse and split)

I did some basic tests on book3e (32 and 64 bit) and didn't see any problems
with this version of the patchset.

-Scott