Re: [PATCH] x86/perf_events: build fix

From: Shaun Ruffell
Date: Thu Dec 27 2012 - 15:02:02 EST


[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@xxxxxxxx>
>
> ---
> 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
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