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From: Keith Owens <kaos@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [RFC Patch]Use ar.kr2 for smp_processor_id
Date: Thu, 08 Feb 2007 06:04:30 +0000	[thread overview]
Message-ID: <6737.1170914670@kao2.melbourne.sgi.com> (raw)
In-Reply-To: <1170905324.3230.7.camel@linux-znh>

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.


  parent reply	other threads:[~2007-02-08  6:04 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-08  3:28 [RFC Patch]Use ar.kr2 for smp_processor_id Zou Nan hai
2007-02-08  4:27 ` Zou Nan hai
2007-02-08  4:59 ` Zou Nan hai
2007-02-08  5:11 ` Zou Nan hai
2007-02-08  6:04 ` Keith Owens [this message]
2007-02-08  6:37 ` Keith Owens
2007-02-08  6:55 ` Keith Owens
2007-02-08  7:14 ` Zou Nan hai
2007-02-08  7:38 ` Zou Nan hai
2007-02-08  8:28 ` peterc
2007-02-08  8:40 ` Keith Owens
2007-02-08 18:03 ` Luck, Tony
2007-02-08 23:59 ` Keith Owens

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