Messages in this thread | | | From | Ramkumar Ramachandra <> | Date | Thu, 3 Oct 2013 18:13:59 +0530 | Subject | Re: [PATCH] perf tool: report user-friendly error from timechart |
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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".
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