* Ramkumar Ramachandra <[email protected]> wrote:
> Ingo Molnar wrote:
> >> + /* Perform a quick sanity check */
> >> + if (!is_valid_tracepoint("power:cpu_frequency")) {
> >> + fprintf(stderr, "Error:\tNo permissions to read
> >> $debugfs/tracing/events/power/cpu_frequency\n");
> >> + fprintf(stderr, "Hint:\tChange the permissions of debugfs:
> >> /sys/kernel/debug\n");
> >> + fprintf(stderr, "\tThe directory will be present if your
> >> kernel was compiled with debugfs support.\n");
> >
> > Is missing permissions the only way how is_valid_tracepoint() can fail?
> >
> > What if debugfs has the right permissions but CONFIG_TRACEPOINTS is
> > disabled in the kernel?
>
> I'm thinking about all this in terms of files present in debugfs. Will
> the cpu_frequecy file be present if tracepoints is disabled? (should I
> quickly check using User-Mode Linux?). If it won't be present, then we
> can just change the last line to "compiled with debugfs and tracepoints
> support".
The debug/tracing/events directory won't be present if tracing is
disabled.
Thanks,
Ingo
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