This makes swap routines operate correctly on the ppc_8xx based machines.
Code has been revalidated on mpc885ads (8M sdram) with recent kernel. Based
on patch from Yuri Tikhonov <[email protected]> to do the same on arch/ppc
instance.
Recent kernel's size makes swap feature very important on low-memory platforms,
those are actually non-operable without it.
Signed-off-by: Yuri Tikhonov <[email protected]>
Signed-off-by: Vitaly Bordug <[email protected]>
---
arch/powerpc/kernel/head_8xx.S | 30 +++++++++++++++++++++++++++++-
include/asm-powerpc/pgtable-ppc32.h | 8 --------
2 files changed, 29 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index f745839..3c9452d 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -332,8 +332,18 @@ InstructionTLBMiss:
mfspr r11, SPRN_MD_TWC /* ....and get the pte address */
lwz r10, 0(r11) /* Get the pte */
+#ifdef CONFIG_SWAP
+ /* do not set the _PAGE_ACCESSED bit of a non-present page */
+ andi. r11, r10, _PAGE_PRESENT
+ beq 4f
+ ori r10, r10, _PAGE_ACCESSED
+ mfspr r11, SPRN_MD_TWC /* get the pte address again */
+ stw r10, 0(r11)
+4:
+#else
ori r10, r10, _PAGE_ACCESSED
stw r10, 0(r11)
+#endif
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 21, 22 and 28 must be clear.
@@ -398,8 +408,17 @@ DataStoreTLBMiss:
DO_8xx_CPU6(0x3b80, r3)
mtspr SPRN_MD_TWC, r11
- mfspr r11, SPRN_MD_TWC /* get the pte address again */
+#ifdef CONFIG_SWAP
+ /* do not set the _PAGE_ACCESSED bit of a non-present page */
+ andi. r11, r10, _PAGE_PRESENT
+ beq 4f
ori r10, r10, _PAGE_ACCESSED
+4:
+ /* and update pte in table */
+#else
+ ori r10, r10, _PAGE_ACCESSED
+#endif
+ mfspr r11, SPRN_MD_TWC /* get the pte address again */
stw r10, 0(r11)
/* The Linux PTE won't go exactly into the MMU TLB.
@@ -507,7 +526,16 @@ DataTLBError:
/* Update 'changed', among others.
*/
+#ifdef CONFIG_SWAP
+ ori r10, r10, _PAGE_DIRTY|_PAGE_HWWRITE
+ /* do not set the _PAGE_ACCESSED bit of a non-present page */
+ andi. r11, r10, _PAGE_PRESENT
+ beq 4f
+ ori r10, r10, _PAGE_ACCESSED
+4:
+#else
ori r10, r10, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
+#endif
mfspr r11, SPRN_MD_TWC /* Get pte address again */
stw r10, 0(r11) /* and update pte in table */
diff --git a/include/asm-powerpc/pgtable-ppc32.h b/include/asm-powerpc/pgtable-ppc32.h
index d1332bb..2c79f55 100644
--- a/include/asm-powerpc/pgtable-ppc32.h
+++ b/include/asm-powerpc/pgtable-ppc32.h
@@ -339,14 +339,6 @@ extern int icache_44x_need_flush;
#define _PMD_PAGE_MASK 0x000c
#define _PMD_PAGE_8M 0x000c
-/*
- * The 8xx TLB miss handler allegedly sets _PAGE_ACCESSED in the PTE
- * for an address even if _PAGE_PRESENT is not set, as a performance
- * optimization. This is a bug if you ever want to use swap unless
- * _PAGE_ACCESSED is 2, which it isn't, or unless you have 8xx-specific
- * definitions for __swp_entry etc. below, which would be gross.
- * -- paulus
- */
#define _PTE_NONE_MASK _PAGE_ACCESSED
#else /* CONFIG_6xx */
--
Sincerely,
Vitaly
On Mar 6, 2008, at 4:53 AM, Vitaly Bordug wrote:
> This makes swap routines operate correctly on the ppc_8xx based
> machines.
> Code has been revalidated on mpc885ads (8M sdram) with recent
> kernel. Based
> on patch from Yuri Tikhonov <[email protected]> to do the same on arch/
> ppc
> instance.
>
> Recent kernel's size makes swap feature very important on low-memory
> platforms,
> those are actually non-operable without it.
>
> Signed-off-by: Yuri Tikhonov <[email protected]>
> Signed-off-by: Vitaly Bordug <[email protected]>
> ---
>
> arch/powerpc/kernel/head_8xx.S | 30 ++++++++++++++++++++++++++
> +++-
> include/asm-powerpc/pgtable-ppc32.h | 8 --------
> 2 files changed, 29 insertions(+), 9 deletions(-)
do we need similar fixes to arch/ppc ?
- k
On Thu, 6 Mar 2008 09:56:58 -0600
Kumar Gala wrote:
>
> On Mar 6, 2008, at 4:53 AM, Vitaly Bordug wrote:
>
> > This makes swap routines operate correctly on the ppc_8xx based
> > machines.
> > Code has been revalidated on mpc885ads (8M sdram) with recent
> > kernel. Based
> > on patch from Yuri Tikhonov <[email protected]> to do the same on
> > arch/ ppc
> > instance.
> >
> > Recent kernel's size makes swap feature very important on
> > low-memory platforms,
> > those are actually non-operable without it.
> >
> > Signed-off-by: Yuri Tikhonov <[email protected]>
> > Signed-off-by: Vitaly Bordug <[email protected]>
> > ---
> >
> > arch/powerpc/kernel/head_8xx.S | 30
> > ++++++++++++++++++++++++++ +++-
> > include/asm-powerpc/pgtable-ppc32.h | 8 --------
> > 2 files changed, 29 insertions(+), 9 deletions(-)
>
> do we need similar fixes to arch/ppc ?
>
there's patch from Yuri that does it for ppc/ - I guess you may just pick it up and place to your tree.
--
Sincerely, Vitaly
> do we need similar fixes to arch/ppc ?
Do we care?
arch/ppc needs many fixes, when you have implemented all of that, you
get a clone of arch/powerpc ;-)
Segher
On Thu, Mar 06, 2008 at 09:56:58AM -0600, Kumar Gala wrote:
> On Mar 6, 2008, at 4:53 AM, Vitaly Bordug wrote:
> > arch/powerpc/kernel/head_8xx.S | 30 ++++++++++++++++++++++++++
> > +++-
> > include/asm-powerpc/pgtable-ppc32.h | 8 --------
> > 2 files changed, 29 insertions(+), 9 deletions(-)
>
> do we need similar fixes to arch/ppc ?
Yes, a patch was posted a while ago.
-Scott
On Mar 6, 2008, at 4:53 AM, Vitaly Bordug wrote:
> This makes swap routines operate correctly on the ppc_8xx based
> machines.
> Code has been revalidated on mpc885ads (8M sdram) with recent
> kernel. Based
> on patch from Yuri Tikhonov <[email protected]> to do the same on arch/
> ppc
> instance.
>
> Recent kernel's size makes swap feature very important on low-memory
> platforms,
> those are actually non-operable without it.
>
> Signed-off-by: Yuri Tikhonov <[email protected]>
> Signed-off-by: Vitaly Bordug <[email protected]>
> ---
>
> arch/powerpc/kernel/head_8xx.S | 30 ++++++++++++++++++++++++++
> +++-
> include/asm-powerpc/pgtable-ppc32.h | 8 --------
> 2 files changed, 29 insertions(+), 9 deletions(-)
applied.
- k