[PATCH 3/5] powerpc: Move plpar_wrappers.h into include/asm-powerpc

[Michael Ellerman]

On Mon, 24 Oct 2005 21:42, Arnd Bergmann wrote:
> On Maandag 24 Oktober 2005 13:09, Michael Ellerman wrote:
> > It looks like those firmware features will only ever be true on pSeries,
> > so we could make it a ppc_md, with everyone except pSeries having a null
> > callback.
>
> I rather thought of making the callback point to set_dabr_spr for
> everything except pSeries and get rid of set_dabr(), but that's just a
> detail.

Mmmm, except then you lose (or obscure) the fact that most platforms just want 
set_dabr_spr(), and that pSeries is the exception. Plus it means you have to 
patch every platform, but you do lose set_dabr() so it's a tradeoff.

> > I'm not sure how crazy we want to get with ppc_md though? It already has
> > 52 members for PPC64, 74 all up.
>
> Yes, that certainly is a problem. It has the potential to become a horrible
> mess if it isn't already. Maybe that should be revisited later, but IMHO
> it seems to be the right abstraction here because it helps get the code
> layering clearer.
>
> There is always a tradeoff between using ppc_md, smp_ops,
> systemcfg->platform, ppc64_firmware_features, cur_cpu_spec->cpu_features
> and compile-time decisions. Maybe we already have too many mechanisms to
> do the same thing (or not enough), and probably we're using the wrong
> abstraction in some places, but figuring that out can become a very long
> discussion...

I agree, we could spend a lot of time talking about it for not much gain. 
Remember Mozilla!

I think we especially don't want to get stuck for too long having these sort 
of discussions while we're trying to do the merge.

In this case I think I will add a ppc_md.set_dabr(), as it means we can make 
an entire header (plpar_wrappers) private to a platform, and that's a Good 
Thing.

But at some point we might need to sit down and try and sort it all out a bit 
more thoroughly.

cheers

-- 
Michael Ellerman
IBM OzLabs

email: michael:ellerman.id.au
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wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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