[PATCH] powerpc/book3e: Fix extlb size

Kumar Gala galak at kernel.crashing.org
Wed Apr 6 11:45:48 EST 2011

On Apr 5, 2011, at 6:39 PM, Benjamin Herrenschmidt wrote:

> On Tue, 2011-04-05 at 07:41 -0500, Kumar Gala wrote:
>>> Rework it to make it a bit clearer, and also correct. We want 3 save
>>> areas, each EX_TLB_SIZE _bytes_.
>> Where does the 3 come from?  I have a guess, and think its possible we
>> (FSL) want 4?
> Wrong guess :-) It's not about exception levels. It's about how much
> the handler can re-enter (2 with E.PT, 3 with virtual linear)
> For MC's, CRITs etc... which we don't support on Book3E 64-bit at this
> stage, you'll have to probably backup the whole area... that or move
> the TLB frame pointer SPR to a separate set of 3 levels, but then you'd
> have to fix the code that makes assumption about level 0 being at a
> fixed offset in the PACA and instead use alignment tricks. We need that
> because that's how we "reset" the TLB frame when a second level finds
> a fault.
> Cheers,
> Ben.

Gotcha, can we add a comment here about what the '3' is about.

- k

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