Re: [PATCH] perf/x86/intel: Fix unwind errors from PEBS entries (mk-II)

[Fubo Chen]

On Thu, Jul 19, 2018 at 2:21 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -143,6 +143,8 @@ enum perf_event_sample_format {
>         PERF_SAMPLE_PHYS_ADDR                   = 1U << 19,
>
>         PERF_SAMPLE_MAX = 1U << 20,             /* non-ABI */
> +
> +       __PERF_SAMPLE_CALLCHAIN_EARLY           = 1UL << 63,
>  };

The above change makes sparse unhappy :-( Sparse reports the following
complaint about __PERF_SAMPLE_CALLCHAIN_EARLY:

./include/uapi/linux/perf_event.h:147:56: warning: cast truncates bits
from constant value (8000000000000000 becomes 0)

Is the above change portable? Isn't a compiler allowed to use 'int' to
represent an enumeration type?

Fubo.