Subject: Re: [PATCH] powerpc/book3e: Fix extlb size

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 06 Apr 2011 09:39:09 +1000

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.