Messages in this thread | | | Date | Sat, 22 Nov 2008 08:30:37 -0500 (EST) | From | Steven Rostedt <> | Subject | Re: Some FTRACE related question |
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On Sat, 22 Nov 2008, Peter Teoh wrote:
> Q1: how to use ftrace to ftrace itself? (i would like to see some > ftrace-triggered flow) In view of the following patch:
ftrace can be very dangerous, (the function tracer part of ftrace). It would be very difficult for ftrace to ftrace itself. When I need to debug ftrace, I use my old tracer logdev:
http://rostedt.homelinux.com/logdev
> > http://linux.derkeiler.com/Mailing-Lists/Kernel/2008-11/msg03745.html > > Is it to prevent this from being possible? > > Q2: how to ftrace s2ram and resume? I attempted to do it, but the > trace output is always filled with "resume" related functions when it > started up, which is only logical.
s2ram does a lot of nasty tricks. On startup, it calls functions before smp_prossor_id() is defined. We use that to disable ftrace recursion (see Q1 ;-). But if you use that in s2ram resume, it will blow up.
Now, you can try to hack ftrace for your own tracing to handle the above problems.
-- Steve
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