Re: [PATCH] x86/perf_events: build fix

[Shaun Ruffell <sruffell@digium.com>]

[forgot to copy lkml]

Hi Jan,

On Fri, Nov 23, 2012 at 04:28:32PM +0000, Jan Beulich wrote:
> At least some older gcc versions dislike mixing constant and non-const
> data in the same section ("... causes a section type confict"). Newer
> gcc simply emits the section as writable (which isn't what we want, but
> also is not a big problem as it gets discarded post-init anyway).
> 
> Also get the Knight's Corner definitions in sync.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> 
> ---
>  arch/x86/kernel/cpu/perf_event_knc.c |    4 ++--
>  arch/x86/kernel/cpu/perf_event_p6.c  |    2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> --- 3.7-rc6/arch/x86/kernel/cpu/perf_event_knc.c
> +++ 3.7-rc6-x86-perf-initconst/arch/x86/kernel/cpu/perf_event_knc.c
> @@ -17,7 +17,7 @@ static const u64 knc_perfmon_event_map[]
>    [PERF_COUNT_HW_BRANCH_MISSES]		= 0x002b,
>  };
>  
> -static __initconst u64 knc_hw_cache_event_ids
> +static const u64 __initconst knc_hw_cache_event_ids
>  				[PERF_COUNT_HW_CACHE_MAX]
>  				[PERF_COUNT_HW_CACHE_OP_MAX]
>  				[PERF_COUNT_HW_CACHE_RESULT_MAX] =
> @@ -284,7 +284,7 @@ static struct attribute *intel_knc_forma
>  	NULL,
>  };
>  
> -static __initconst struct x86_pmu knc_pmu = {
> +static const struct x86_pmu knc_pmu __initconst = {
>  	.name			= "knc",
>  	.handle_irq		= knc_pmu_handle_irq,
>  	.disable_all		= knc_pmu_disable_all,
> --- 3.7-rc6/arch/x86/kernel/cpu/perf_event_p6.c
> +++ 3.7-rc6-x86-perf-initconst/arch/x86/kernel/cpu/perf_event_p6.c
> @@ -19,7 +19,7 @@ static const u64 p6_perfmon_event_map[]
>  
>  };
>  
> -static __initconst u64 p6_hw_cache_event_ids
> +static const u64 __initconst p6_hw_cache_event_ids
>  				[PERF_COUNT_HW_CACHE_MAX]
>  				[PERF_COUNT_HW_CACHE_OP_MAX]
>  				[PERF_COUNT_HW_CACHE_RESULT_MAX] =
> 
> 
> 
> --

I was testing out 3.8-rc1 when I ran into the same problem resolved
by this patch when building with gcc (GCC) 4.1.2 20080704 (Red Hat
4.1.2-51)

Were you given a reason why this shouldn't be needed?

It looks like the build error was introduced by (e09df47 "perf/x86:
Update/fix generic events on P6 PMU") which is in v3.7 as well.

Thanks,
Shaun