[PATCH] ppc44x: support for 256K PAGE_SIZE

[Josh Boyer]

On Thu, 18 Oct 2007 21:45:14 +1000
Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:

> 
> On Thu, 2007-10-18 at 05:44 -0500, Josh Boyer wrote:
> > On Thu, 2007-10-18 at 11:08 +0400, Yuri Tikhonov wrote:
> > >  Hello,
> > > 
> > >  The following patch adds support for 256KB PAGE_SIZE on ppc44x-based boards. 
> > > The applications to be run on the kernel with 256KB PAGE_SIZE have to be 
> > > built using the modified version of binutils, where the MAXPAGESIZE 
> > > definition is set to 0x40000 (as opposite to standard 0x10000).
> > 
> > Sorry, this is against arch/ppc which is bug fix only.  New features
> > should be done against arch/powerpc.  Also, I'd rather see something
> > along the lines of hugetlbfs support instead.
> 
> I slightly disagree on that one. It does make sense in embedded
> applications to use larger page sizes like that to compensate for small
> TLBs, and hugetlbfs has serious constraints that may well make it
> impractical.

Out of curiosity, what constraints are those?

> Based on that, I'd be tempted to let that in provided it doesn't
> requires ugly hacks, which seems to be the case. It still needs to be
> adapted to arch/powerpc however, and get closer scrutiny that I didn't
> have time to do yet.
> 
> You are the maintainer, so you decide, but my opinion here is that
> wanting that is fair enough.

I always reserve the right to change my mind.  If something makes sense
and the code is decent enough then it might very well be acceptable.
Requiring a modified binutils makes me a bit nervous though.

josh