Subject: Re: [PATCH] powerpc: remove default=y from PMAC and CHRP Kconfigs

From: Matt Sealey <[email-masked]>
Date: Thu, 09 Oct 2008 10:59:05 -0500

Timur Tabi wrote:
> Benjamin Herrenschmidt wrote:
> 
>> I'm happy with -all- platforms for a given CPU type defaulting to y. 
> 
> I'm not sure I understand.  The current Kconfigs defaults to Y for CHRP and PMAC
> on *all* PowerPC systems, including those that are neither CHRP nor PMAC.  Are
> you saying that's a good thing?

Timur,

You do realise it's entirely possible to build a kernel which supports 50
different Freescale CPUs all in one?

Enabling CHRP, PMAC support *AND* non-CHRP platforms is possible in the same
binary. The relevant code that differentiates them is in the boot wrapper
and this is selected by *how you compile the kernel* and not which objects
are compiled in. make zImage and make cuImage on the same kernel objects
will give you an 'identical' image just packaged in a different way.

If you really want to build a single-cpu single-board kernel, disable CHRP
and PMAC for those board configs, but the default definitely should be to
enable them all within reason (obviously coherent and non-coherent designs
cannot coexist in the same kernel, 32-bit and 64-bit do not play well in
the same kernel..)

-- 
Matt Sealey <[email-masked]>
Genesi, Manager, Developer Relations