Re: [RFC Patch]Use ar.kr2 for smp_processor_id

From: Keith Owens <kaos_at_sgi.com>
Date: 2007-02-08 17:04:30
Zou Nan hai (on 08 Feb 2007 11:28:44 +0800) wrote:
>Pin ar.kr2 of each CPU, so that smp_processor_id can use it.

Historically ar.k2 has been reserved for debugging purposes, for
example in ivt.S.  Debuggers often need a location that can be used to
track progress, it has to be somewhere that does not rely on TLB
entries and is guaranteed to appear in MCA/INIT records - ar.k2 is
perfect for this.

Use Tony's suggestion of testing for a change in ar.k3 (guaranteed to
be unique on every cpu) and caching the corresponding cpu number when
it changes.

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Received on Thu Feb 08 17:04:52 2007

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