From: Peng Fan <van.freenix@gmail.com>
To: Wei Chen <wei.chen@linaro.org>
Cc: julien.grall@arm.com, 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 20:37:37 +0800 [thread overview]
Message-ID: <20160525123727.GA18234@linux-7smt.suse> (raw)
In-Reply-To: <1464142211-343-1-git-send-email-Wei.Chen@linaro.org>
Hi Wei,
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?
Regards,
Peng.
>
>Signed-off-by: Wei Chen <Wei.Chen@linaro.org>
>---
> xen/arch/arm/arm64/head.S | 1 -
> 1 file changed, 1 deletion(-)
>
>diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
>index 3090beb..91e2817 100644
>--- a/xen/arch/arm/arm64/head.S
>+++ b/xen/arch/arm/arm64/head.S
>@@ -267,7 +267,6 @@ common_start:
> * find that multiprocessor extensions are
> * present and the system is SMP */
> mrs x0, mpidr_el1
>- tbz x0, _MPIDR_SMP, 1f /* Multiprocessor extension not supported? */
> tbnz x0, _MPIDR_UP, 1f /* Uniprocessor system? */
>
> ldr x13, =(~MPIDR_HWID_MASK)
>--
>2.7.4
>
>
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@lists.xen.org
>http://lists.xen.org/xen-devel
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next prev parent reply other threads:[~2016-05-25 12:37 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 [this message]
2016-05-25 13:31 ` Julien Grall
2016-05-25 14:11 ` Julien Grall
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