From: Paul Mackerras <paulus@ozlabs.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Paul Mackerras via Linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [RFC PATCH 0/9] powerpc/mm: Restructure Linux PTE on Book3S/64 to radix format
Date: Mon, 22 Feb 2016 09:31:56 +1100 [thread overview]
Message-ID: <20160221223156.GA30309@fergus.ozlabs.ibm.com> (raw)
In-Reply-To: <87povq7boi.fsf@linux.vnet.ibm.com>
On Sun, Feb 21, 2016 at 01:11:17PM +0530, Aneesh Kumar K.V wrote:
> "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:
>
> > Paul Mackerras <paulus@samba.org> writes:
> >
> >> This patch series modifies the Linux PTE format used on 64-bit Book3S
> >> processors (i.e. POWER server processors) to make the bits line up
> >> with the PTE format used in the radix trees defined in PowerISA v3.0.
> >> This will reduce the amount of further change required to make a
> >> kernel that can run with either a radix MMU or a hashed page table
> >> (HPT) MMU.
> >>
> >> This also changes the upper levels of the tree to use real addresses
> >> rather than kernel virtual addresses - that is, we no longer have the
> >> 0xc000... at the top of each PGD/PUD/PMD entry. I made this change
> >> for all 64-bit machines, both embedded and server.
> >>
> >> The patch series is against v4.5-rc4 plus Aneesh's "powerpc/mm/hash:
> >> Clear the invalid slot information correctly" patch.
> >>
> >> I have compiled this for all the defconfigs in the tree, without
> >> error. I have tested this, with the fixes branch of the powerpc tree
> >> merged in, both running bare-metal on a POWER8 and in a KVM guest on
> >> that POWER8 system. In the guest I tested both 4k and 64k configs,
> >> with THP enabled; in the host I tested with 64k page size and THP
> >> enabled. All these tests ran fine, including running a KVM guest on
> >> the bare-metal system. So far I have done kernel compiles in a loop
> >> as the test, but I plan to run LTP and possibly some other tests.
> >>
> >> Comments welcome.
> >
> > I was expecting some complex changes in asm and other part of the code. That
> > is one of the reason I was holding of a series like this till I get the
> > radix merged. I should have really tried the radix/hash linux page table
> > consolidation to see the impact.
>
> One of the details that i hit last time with _PAGE_PTE was the usage of
> @h symbol in asm code. I did a quick look and I guess we are ok. But it
> will be good to double check. pmdp_splitting_flush (which got removed)
> had usages like %4@h etc
I have done some pretty thorough grepping in arch/powerpc. There is
no assembly code left that manipulates Linux PTEs (on 64-bit Book 3S,
that is), because you converted it all to C code. :) There are a
couple of bits of inline asm, but the only bit that is used as an
immediate value is _PAGE_BUSY, which goes from 0x800 to 0x200, and
could actually stay at 0x800 in fact.
Paul.
next prev parent reply other threads:[~2016-02-21 22:46 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-20 6:12 [RFC PATCH 0/9] powerpc/mm: Restructure Linux PTE on Book3S/64 to radix format Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 1/9] powerpc/mm/book3s-64: Clean up some obsolete or misleading comments Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 2/9] powerpc/mm/book3s-64: Free up 7 high-order bits in the Linux PTE Paul Mackerras
2016-02-20 16:16 ` Aneesh Kumar K.V
2016-02-21 22:43 ` Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 3/9] powerpc/mm/64: Use physical addresses in upper page table tree levels Paul Mackerras
2016-02-20 16:35 ` Aneesh Kumar K.V
2016-02-21 22:45 ` Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 4/9] powerpc/mm/book3s-64: Move _PAGE_PRESENT to the most significant bit Paul Mackerras
2016-02-20 8:33 ` kbuild test robot
2016-02-20 16:41 ` Aneesh Kumar K.V
2016-02-21 22:40 ` Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 5/9] powerpc/mm/book3s-64: Move _PAGE_PTE to 2nd " Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 6/9] powerpc/mm/book3s-64: Move HPTE-related bits in PTE to upper end Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 7/9] powerpc/mm/book3s-64: Shuffle read, write, execute and user bits in PTE Paul Mackerras
2016-02-21 7:30 ` Aneesh Kumar K.V
2016-02-21 22:36 ` Paul Mackerras
2016-02-22 0:27 ` Michael Ellerman
2016-02-20 6:12 ` [RFC PATCH 8/9] powerpc/mm/book3s-64: Move software-used " Paul Mackerras
2016-02-20 6:12 ` [RFC PATCH 9/9] powerpc/mm/book3s-64: Expand the real page number field of the Linux PTE Paul Mackerras
2016-02-20 14:40 ` [RFC PATCH 0/9] powerpc/mm: Restructure Linux PTE on Book3S/64 to radix format Aneesh Kumar K.V
2016-02-20 15:32 ` Aneesh Kumar K.V
2016-02-21 7:41 ` Aneesh Kumar K.V
2016-02-21 22:31 ` Paul Mackerras [this message]
2016-02-22 0:30 ` Michael Ellerman
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