Re: [PATCH] x86: Fix boot on uniprocessor systems

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 25 Mar 2014 01:59:10 +0300 Artem Fetishev <artem_fetishev@epam.com> wrote:

> On x86 uniprocessor systems topology_physical_package_id() returns -1 which
> causes rapl_cpu_prepare() to leave rapl_pmu variable uninitialized which leads
> to GPF in rapl_pmu_init(). See arch/x86/kernel/cpu/perf_event_intel_rapl.c.
> 
> It turns out that physical_package_id and core_id can actually be retreived for
> uniprocessor systems too. Enabling them also fixes rapl_pmu code.
> 
> Signed-off-by: Artem Fetishev <artem_fetishev@epam.com>
> ---
> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index d35f24e..1306d11 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -119,9 +119,10 @@ static inline void setup_node_to_cpumask_map(void) { }
>  
>  extern const struct cpumask *cpu_coregroup_mask(int cpu);
>  
> -#ifdef ENABLE_TOPO_DEFINES
>  #define topology_physical_package_id(cpu)	(cpu_data(cpu).phys_proc_id)
>  #define topology_core_id(cpu)			(cpu_data(cpu).cpu_core_id)
> +
> +#ifdef ENABLE_TOPO_DEFINES
>  #define topology_core_cpumask(cpu)		(per_cpu(cpu_core_map, cpu))
>  #define topology_thread_cpumask(cpu)		(per_cpu(cpu_sibling_map, cpu))
>  #endif

The patch applies to 3.13 and perhaps earlier kernels.  Is it needed in
those kernel versions?