From: Julien Grall <julien.grall@arm.com>
To: Peng Fan <van.freenix@gmail.com>, Wei Chen <wei.chen@linaro.org>
Cc: sstabellini@kernel.org, steve.capper@arm.com, xen-devel@lists.xen.org
Subject: Re: [PATCH 4/4] xen/arm: arm64: Remove MPIDR multiprocessing extensions check
Date: Wed, 25 May 2016 14:31:06 +0100 [thread overview]
Message-ID: <5745A91A.7010808@arm.com> (raw)
In-Reply-To: <20160525123727.GA18234@linux-7smt.suse>
Hello Peng,
On 25/05/16 13:37, Peng Fan wrote:
> On Wed, May 25, 2016 at 10:10:11AM +0800, Wei Chen wrote:
>> In ARM64, the MPIDR multiprocessing extensions bit is reserved to 1.
>> So, the value check for this bit is no longer necessary on ARM64.
>
> From ARM DDI0487A.G, I found the U bit for MPIDR_EL1:
> "
> Indicates a Uniprocessor system, as distinct from PE 0 in a multiprocessor system. The possible
> values of this bit are:
> 0 Processor is part of a multiprocessor system.
> 1 Processor is part of a uniprocessor system.
> "
>
> It's not reserved to 1. Which doc are you refering to?
Please read carefully the patch. The check on MPDIR_EL1.U is kept, only
the check to the RES1 bit ('M' for Aarch32) is removed.
Regards,
--
Julien Grall
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next prev parent reply other threads:[~2016-05-25 13:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-25 2:10 [PATCH 4/4] xen/arm: arm64: Remove MPIDR multiprocessing extensions check Wei Chen
2016-05-25 12:37 ` Peng Fan
2016-05-25 13:31 ` Julien Grall [this message]
2016-05-25 14:11 ` Julien Grall
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