Re: [PATCH v2 1/8] perf/x86: add a function to get the lbr stack

[Wei Wang]

On 09/07/2018 11:28 AM, Andi Kleen wrote:
+int perf_get_lbr_stack(struct perf_lbr_stack *stack)
+{
+       stack->lbr_nr = x86_pmu.lbr_nr;
+       stack->lbr_tos = x86_pmu.lbr_tos;
+       stack->lbr_from = x86_pmu.lbr_from;
+       stack->lbr_to = x86_pmu.lbr_to;
+
+       if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
+               stack->lbr_info = MSR_LBR_INFO_0;
+       else
+               stack->lbr_info = 0;
Seems weird to export the enum value if the enum isn't exported.
How can it be used?

I'm not sure about the issue. The caller gets the value of 
MSR_LBR_INFO_0 (not the enum, LBR_FORMAT_INFO) only when the hardware 
supports it. If hardware doesn't support it, just sets it to 0, and 
there will be no lbr info msr to be passed through.

Best,
Wei