From mboxrd@z Thu Jan  1 00:00:00 1970
From: Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v2 1/5] ARM: kernel: smp_setup_processor_id() updates
Date: Fri, 9 Nov 2012 14:44:46 +0000
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To: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>, Nicolas Pitre <nicolas.pitre@linaro.org>, Dave Martin <dave.martin@linaro.org>, Kukjin Kim <kgene.kim@samsung.com>, Russell King <linux@arm.linux.org.uk>, Pawel Moll <Pawel.Moll@arm.com>, Stephen Warren <swarren@wwwdotorg.org>, Tony Lindgren <tony@atomide.com>, Catalin Marinas <Catalin.Marinas@arm.com>, "devicetree-discuss@lists.ozlabs.org" <devicetree-discuss@lists.ozlabs.org>, Magnus Damm <magnus.damm@gmail.com>, Amit Kucheria <amit.kucheria@linaro.org>, Grant Likely <grant.likely@secretlab.ca>, "rob.herring@calxeda.com" <rob.herring@calxeda.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, David Brown <davidb@codeaurora.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
List-Id: devicetree@vger.kernel.org

On Fri, Nov 09, 2012 at 02:34:10PM +0000, Lorenzo Pieralisi wrote:
> This patch applies some basic changes to the smp_setup_processor_id()
> ARM implementation to make the code that builds cpu_logical_map more
> uniform across the kernel.
> 
> The function now prints the full extent of the boot CPU MPIDR[23:0] and
> initializes the cpu_logical_map for CPUs up to nr_cpu_ids.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> ---
>  arch/arm/kernel/setup.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index da1d1aa..ede7c84 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -426,13 +426,14 @@ int __cpu_logical_map[NR_CPUS];
>  void __init smp_setup_processor_id(void)
>  {
>  	int i;
> -	u32 cpu = is_smp() ? read_cpuid_mpidr() & 0xff : 0;
> +	u32 mpidr = read_cpuid_mpidr() & 0xffffff;

We need that is_smp() check, otherwise we'll go and do a funky CP15
operation on CPU's that might not be too happy about it.

Will