Messages in this thread |  | | Date | Sat, 22 Mar 2008 16:16:48 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: tracing and mmiotrace |
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Hi Pekka,
I'm on vacation at the moment, but will start up helping Ingo with ftrace on Monday.
On Sat, 22 Mar 2008, Pekka Paalanen wrote:
> > > > that's weird - _entry_ is NULL? > > Yes. See the patch, and my kernel log at > http://jumi.lut.fi/~paalanen/scratch/tracing-dmesg1.txt > > First you see my check in __trace_special() trigger, and then NULL > pointer dereference BUG at ffffffff80259332 which translates to > kernel/trace/trace.c:639 in tracing_generic_entry_update(), line: > entry->preempt_count = pc & 0xff; > I don't understand why it tries to dereference NULL even when I > check for it.
Interesting. I'll have to look into that more on Monday.
> > --- > Oh, and during bootup there is an error about -fstack-protector-all > test failed. > > > > btw. currently 'cat /debug/tracing/trace' gives the > > > print_func_help_header() and quits, it never stays waiting for more > > > data. > > > > yeah - try "cat /debug/tracing/trace_pipe" for the waiting variant - > > does that work better? > > Not really. IIRC it said "resource temporarily unavailable" until > mmiotrace actually tried to produce data. No header there. So I > cannot make "cat" ready to read and after that start tracing.
I'll have to clean up the trace_pipe code to be a bit more robust.
Thanks for doing this. I'll be getting more involved starting Monday.
-- Steve
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