Messages in this thread | | | Date | Mon, 03 Nov 2014 21:30:27 -0500 | From | Peter Hurley <> | Subject | Re: [PATCH] ftrace: Document ftrace command line limitations |
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On 11/03/2014 09:14 PM, Steven Rostedt wrote: > On Mon, 3 Nov 2014 20:45:25 -0500 > Peter Hurley <peter@hurleysoftware.com> wrote: > >> When using the function or function_graph tracers from the command >> line, certain command line options have limitations. >> >> Document that only kernel built-in functions can be filtered via >> ftrace_filter= or ftrace_graph_filter=. Also document that tracer- >> specific options cannot be set on the command line via trace_options. > > It's not just a command line limitation. The command line behaves > exactly like set_ftrace_filter does. That is, it only affects the > functions that are loaded when the filter is modified. It never updates > functions that will be loaded when modules are. > > Adding this documentation makes it seem that set_ftrace_filter has the > ability to update functions that were not loaded yet. This is not true. > The command line filtering behaves exactly like set_ftrace_filter does. > It only enables the functions that are loaded at the time the function > is set. Which was at boot up, and it just happens to be only built in > functions at that time.
Ah, ok. I'll clarify those two lines and add to the documentation in Documentation/trace/ftrace.txt
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