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Subject: Re: [PATCH v2] powerpc/setup_{32, 64}.c: remove unneeded
 boot_cpuid{, _phys}
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Scott Wood <scottwood@freescale.com>
Date: Sat, 17 Dec 2011 09:09:44 +1100
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On Fri, 2011-12-16 at 15:29 -0600, Scott Wood wrote:
> It would be nice if we could eliminate all usage of the boot cpu dtb
> field -- it's easy to forget to set it, especially if you're not making
> an AMP config.  The default -1 means this patch would break booting with
> such a tree.
> 
> If we don't want to record the PIR of the first CPU to enter as the boot
> CPU (is the concern implementations where the CPU node's reg is not the
> same as what's in PIR?), how about just having a variable that gets set
> before releasing secondaries?  If you're in the boot entry code and that
> variable is set, you're a secondary.  Or, use a distinct release address
> for secondaries rather than __early_start.

Of course you can only do that on processors that have a reliable
PIR :-)

Cheers,
Ben.