On Sat, 13 Dec 2014 11:59:25 +0100 Borislav Petkov <b...@alien8.de> wrote:
> On Sat, Dec 13, 2014 at 12:50:37AM -0500, Steven Rostedt wrote: > > > > Add the kernel command line tracepoint_printk option that will > > have tracepoints that are active sent to printk(). > > > > Passing "tracepoint_printk" will activate this. To turn it off > > the sysctl /proc/sys/kernel/tracepoint_printk can have '0' echoed > > into it. Note, this only works if the cmdline option is used. > > Echoing 1 into the sysctl file without the cmdline option will > > have no affect. > > > > Note, this is a dangerous option. Having high frequency > > tracepoints send their data to printk() can possibly cause > > a live lock. > > > > Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos > > > > Suggested-by: Thomas Gleixner <t...@linutronix.de> > > Signed-off-by: Steven Rostedt <rost...@goodmis.org> > > --- > > Documentation/kernel-parameters.txt | 18 ++++++++++++++++++ > > include/linux/ftrace.h | 1 + > > kernel/sysctl.c | 7 +++++++ > > kernel/trace/trace.c | 17 +++++++++++++++++ > > kernel/trace/trace.h | 1 + > > kernel/trace/trace_events.c | 32 ++++++++++++++++++++++++++++++++ > > 6 files changed, 76 insertions(+) > > > > diff --git a/Documentation/kernel-parameters.txt > > b/Documentation/kernel-parameters.txt > > index 1d09eb37c562..d81f464a7358 100644 > > --- a/Documentation/kernel-parameters.txt > > +++ b/Documentation/kernel-parameters.txt > > @@ -3500,6 +3500,24 @@ bytes respectively. Such letter suffixes can also be > > entirely omitted. > > See also Documentation/trace/ftrace.txt "trace options" > > section. > > > > + tracepoint_printk[FTRACE] > > Damn, this is long and most likely nasty to type on some dingy box when > you're trying to debug stuff. Can we shorten it? > > trace_printk No this is already taken. > tp_printk Actually, I was thinking about shortening it to tp_printk. > tp_print > tp_pr > ... > > Last one is my favourite - we should call it ToiletPaper_Print :-) What you need when your kernel is in the crapper. -- Steve > > > + Have the tracepoints sent to printk as well as the > > + tracing ring buffer. This is useful for early boot up > > + where the system hangs or reboots and does not give the > > + option for reading the tracing buffer or performing a > > + ftrace_dump_on_oops. > -- 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/
