Becky Bruce wrote:
I'm pretty sure I went through this in great detail at one point and
concluded that I did in fact need the lwarx/stwcx. IIRC, it has to do
with other non-set_pte_at writers not necessarily holding the page table
lock. FYI, the existing 32-bit PTE code is doing atomic updates as well.
But will those updates happen if there isn't already a valid PTE?
About PTE_ATOMIC_UPDATES, I didn't add that in because hashed page table
implementations require atomic updates.
Right, I misread it and thought it was being used for non-hashed
implementations as well.
What happens if you enable 64-bit PTEs on a 603-ish CPU? The kconfig
seems to allow it.
Adding it in would create
another clause in that code, because I would still need to order the
operations with a 64-bit PTE and I can't call pte_update as it only
changes the low word of the pte. I wasn't feeling too keen on adding
untested pagetable code into the kernel :)
Wimp. :-)
> I can add it if the peanut
gallery wants it, but I'll be marking it with a big fat "BUYER BEWARE".
No, there's little point if nothing selects it (or is planned to in the
near future).
diff --git a/arch/powerpc/platforms/Kconfig.cputype
b/arch/powerpc/platforms/Kconfig.cputype
index 7f65127..ca5b58b 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -128,18 +128,22 @@ config FSL_EMB_PERFMON
config PTE_64BIT
bool
- depends on 44x || E500
+ depends on 44x || E500 || 6xx
default y if 44x
- default y if E500 && PHYS_64BIT
+ default y if PHYS_64BIT
How is this different from PHYS_64BIT?
One is the width of the PTE and one is the width of a physical address.
It's entirely plausible to have a 64-bit PTE because you have a bunch of
status bits, and only have 32-bit physical addressing. That's why there
are 2 options.
Right, I just didn't see anything that actually selects it independently
of PHYS_64BIT. Is this something that's expected to actually happen in
the future?
The "default y if 44x" line is redundant with the "default y if PHYS_64BIT".
config PHYS_64BIT
- bool 'Large physical address support' if E500
- depends on 44x || E500
+ bool 'Large physical address support' if E500 || 6xx
Maybe "if !44x", or have 44x "select" this, rather than listing all
arches where it's optional.
Not sure exactly what you're suggesting here........
It just seems simpler to not conditionalize the bool, but instead have
CONFIG_44x do "select PHYS_64BIT". I'd rather avoid another list of
platforms accumulating in a kconfig dependency.
+ depends on 44x || E500 || 6xx
select RESOURCES_64BIT
default y if 44x
---help---
This option enables kernel support for larger than 32-bit physical
- addresses. This features is not be available on all e500 cores.
+ addresses. This features is not be available on all cores.
"This features is not be"?
Heh, I didn't type that :) But I can fix it.
You didn't type it, but you touched it. Tag, you're it. :-)
-Scott
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