On Aug 22, 2008, at 4:17 AM, Kumar Gala wrote:
On Aug 22, 2008, at 3:08 AM, Christian Ehrhardt wrote:
Scott Wood wrote:
On Thu, Aug 21, 2008 at 09:21:39AM -0500, Kumar Gala wrote:
Where is the other discussion? I'd like to understand what's
going on here.. (especially since I added the wrtee[i] changes
to kernel way back when).
Presumably, they want to be able to replace wrtee with a store to a
hypervisor/guest shared memory area, and there's no store-immediate
instruction.
-Scott
Exactly Scott
And for your question Kumar, in the last submission I was asked to
split host and guest patches.
So the host discussion lives on kvm-ppc@xxxxxxxxxxxxxxx as I
mentioned (maybe a bit too hidden)
in the [0/4] mail of this series.
Maybe I'm missing something but it seems like just changing the code
to wrtee isn't the best way to ensure you have enough space to put
the set of instructions you guys want.
Sorry, I have not really been following this, I assume you are
replacing SPR accesses with load/stores that do not trap.
I believe thats fine for reading any SPR, but not true for modifying
some SPRs, particularly MSR.
IMHO you must trap on any instruction that modifies the MSR.
So you should prolly not rewrite mtmsr or wrtee* but let them trap.
BTW: actually moving problem SPRs (like MSRs) to a read only page
makes decoding far more efficient, but it does burn another TLB entry.
-JX
- k
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