Re: [PATCH 2/4] powerpc: Fix 32 bits mm operations when not using BATs

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Thu, 2007-03-22 at 23:00 +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2007-03-22 at 12:55 +0100, Segher Boessenkool wrote:
> > > +	 * If the hash table bucket is full of kernel text entries, we'll
> > > +	 * lockup here but that shouldn't happen
> > 
> > On 32-bit we have room for one HPTE per real page -- assuming
> > the kernel text is fully enclosed inside one power-of-two
> > size and aligned range of address space (i.e. always ;-) ),
> > a lockup here _cannot_ happen.  It doesn't get tight until you
> > start using all of memory as kernel text.
> 
> I know, which is why "shouldn't" is a good enough choice of word :-)
> 
> > So replace this comment with something like "the HTAB is
> > sized such that no PTEG can overflow from kernel text alone"?
> > It sounds a lot less hand-wavy than "but this shouldn't happen".

Note that there is still a potential of a second entry due to the
secondary group but that wouldn't happen in practice :-)

Ben.