Subject: Re: get_pteptr prototype

From: David Gibson <[email-masked]>
Date: Thu, 9 Jan 2003 13:33:00 +1100

On Wed, Jan 08, 2003 at 06:11:25PM -0600, Hollis Blanchard wrote:
>
> On Wed, 2003-01-08 at 17:49, David Gibson wrote:
> > On Wed, Jan 08, 2003 at 09:48:48AM -0600, Hollis Blanchard wrote:
> > > It's simply a wrapper around successive pte/pmd/pgd_offset calls, with
> > > some error checking. Are you saying those calls are not the correct way
> > > to get the PTE pointer for an address?
> >
> > Trouble is that this will break badly in 2.5 where we use large-page
> > entries for the lowmem mapping.
>
> I'm happy to change it to something 2.5-friendly if someone can suggest
> how...
>
> Alternatively I can add 405LP to the XMON/KGDB/BDI2000 list of ifdefs
> that map the whole kernel writable, which would be overkill but avoid
> adding PTE manipulations.

Hmm... what's the reason that wakeup_info needs to be reserved in
head_4xx.S, rather than just being a normal variable in the data area
(which should be writable anyway)?  Its not obvious to me from the
patch.

Actually, skimming through the patch I noticed a minor nit: you only
have one .long in head_4xx.S reserving space for the wakeup_info
struct which is 3 words long.  In practice the . = in the exception
handlers will give you plenty of space, but I think it would be good
form to explicitly reserve the right amount of space.

--
David Gibson			| For every complex problem there is a
[email-masked]	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson

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