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SubjectRe: [PATCH 04/19] ARM64 / ACPI: Introduce arch_fix_phys_package_id() for cpu topology


On 24/07/14 14:00, Hanjun Guo wrote:
> arch_fix_phys_package_id() will be called in ACPI core to use
> the slot number provided by ACPI to update the physical package
> id, then we can get the right value in the "physical id" field
> of /proc/cpuinfo.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
> arch/arm64/include/asm/topology.h | 2 ++
> arch/arm64/kernel/topology.c | 14 ++++++++++++++
> 2 files changed, 16 insertions(+)
>
> diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
> index 7ebcd31..2b216d4 100644
> --- a/arch/arm64/include/asm/topology.h
> +++ b/arch/arm64/include/asm/topology.h
> @@ -23,11 +23,13 @@ extern struct cpu_topology cpu_topology[NR_CPUS];
> void init_cpu_topology(void);
> void store_cpu_topology(unsigned int cpuid);
> const struct cpumask *cpu_coregroup_mask(int cpu);
> +void arch_fix_phys_package_id(int num, u32 slot);
>
> #else
>
> static inline void init_cpu_topology(void) { }
> static inline void store_cpu_topology(unsigned int cpuid) { }
> +static inline void arch_fix_phys_package_id(int num, u32 slot) { }
>
> #endif
>
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 43514f9..c547885 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -281,3 +281,17 @@ void __init init_cpu_topology(void)
> if (parse_dt_topology())
> reset_cpu_topology();
> }
> +
> +/*
> + * Use the CPU slot number provided by ACPI to update the physical
> + * package id when cpuid_topo->cluster_id is not available, then we
> + * can get the right value in the "physical id" field of /proc/cpuinfo.
> + */

We don't have "physical id" field in /proc/cpuinfo on ARM64.

> +void arch_fix_phys_package_id(int num, u32 slot)
> +{
> + struct cpu_topology *cpuid_topo = &cpu_topology[num];
> +
> + if (cpuid_topo->cluster_id == -1)
> + cpuid_topo->cluster_id = slot;
> +}
> +EXPORT_SYMBOL_GPL(arch_fix_phys_package_id);
>

The ACPI core uses this function to set the package id as read from
_SUN from the device. As per spec, _SUN is used by OSPM UI to identify
slots for the user. Do we know how will this be used on ARM64 ?

If not clear at this time, better to define it or keep it empty. I see
even x86 does nothing in that function.

Regards,
Sudeep



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