On Tue, 4 Nov 2014 12:46:05 -0500 Peter Hurley <pe...@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=. Document that tracer-specific > options cannot be set on the command line via trace_options. > Document that ftrace cannot do late binding for function > filters. > > Signed-off-by: Peter Hurley <pe...@hurleysoftware.com> > --- > Documentation/kernel-parameters.txt | 6 ++++++ > Documentation/trace/ftrace.txt | 7 +++++-- > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt > b/Documentation/kernel-parameters.txt > index 4c81a86..d098ead 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -1121,6 +1121,7 @@ bytes respectively. Such letter suffixes can also be > entirely omitted. > list of functions. This list can be changed at run > time by the set_ftrace_filter file in the debugfs > tracing directory. > + Only kernel built-in functions can be filtered. > > ftrace_notrace=[function-list] > [FTRACE] Do not trace the functions specified in > @@ -1134,6 +1135,7 @@ bytes respectively. Such letter suffixes can also be > entirely omitted. > function-list is a comma separated list of functions > that can be changed at run time by the > set_graph_function file in the debugfs tracing > directory. > + Only kernel built-in functions can be filtered. > > ftrace_graph_notrace=[function-list] > [FTRACE] Do not trace from the functions specified in > @@ -3521,6 +3523,10 @@ bytes respectively. Such letter suffixes can also be > entirely omitted. > > trace_options=stacktrace > > + Tracer-specific options are ignored when set this way. > + For example, the 'func_stack_trace' option cannot be > + set here. > + > See also Documentation/trace/ftrace.txt "trace options" > section. > > diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt > index 4da4261..d540273 100644 > --- a/Documentation/trace/ftrace.txt > +++ b/Documentation/trace/ftrace.txt > @@ -188,7 +188,8 @@ of ftrace. Here is a list of some of the key files: > in with practically no overhead in performance. This also > has a side effect of enabling or disabling specific functions > to be traced. Echoing names of functions into this file > - will limit the trace to only those functions. > + will limit the trace to only those functions. Only already- > + loaded functions can be filtered. I would add a little more. Something that states that modules with the same function names that are loaded at a later time will not be filtered with theses names. Hmm, actually, I think this could be rather trivial to implement something that will filter modules that are added. I think that may be a better solution. I'm assuming you would like to have functions filtered via the command line to filter on modules as well. Correct? -- Steve > > This interface also allows for commands to be used. See the > "Filter commands" section for more details. > @@ -208,7 +209,9 @@ of ftrace. Here is a list of some of the key files: > > Set a "trigger" function where tracing should start > with the function graph tracer (See the section > - "dynamic ftrace" for more details). > + "dynamic ftrace" for more details). As with set_ftrace_filter, > + only names of already-loaded functions can be written to > + this file. > > available_filter_functions: > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/