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Subject: Re: _extending_ platform support options?
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Josh Boyer <jwboyer@linux.vnet.ibm.com>
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Date: Thu, 02 Dec 2010 07:57:02 +1100
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On Wed, 2010-12-01 at 08:47 -0500, Josh Boyer wrote:
> >Though, to me, it does not seem really OK to assign ppc_md members
> >that way. The original struct machdep for "virtex" (which is defined
> >in virtex.c with define_machine()) is not adjusted either. Ok, we
> >could modify that one, too.
> >Especially I'm not sure if it is OK to use machine_core_initcall()
> for such modifications.
> >
> >So my question is: Is there any recommended way for doing such
> >"extensions"? Or is it OK to just duplicate virtex.c (which does not
> >seem really OK, too)?
> 
> Duplicate it as you have done, naming the file something unique.  We
> try
> to prevent unnecessary duplication of code, but sometimes it's cleaner
> to just have a separate board file instead. 

Right. Best way is to turn the common code in virtex.c into "library"
code that you can hookup from your platform's ppc_md, so you avoid
duplication that way for most things.

You an do that by just linking in virtex.c and changing the stuff you
want to be non-static, or better if that becomes a habit, separate
virtex-lib.c (for example) from virtex-simple.c (generic platform for
example). You don't have to follow my proposed names :-)

Cheers,
Ben.