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| author | Stephen Kitt <steve@sk2.org> | 2020-04-29 22:57:56 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2020-05-05 09:53:45 -0600 |
| commit | 50cdae76b8d021f31ea07af3bb30983486b79df8 (patch) | |
| tree | 432b079776db2780d18dc5764b05510ffcd2ea14 /Documentation | |
| parent | c624adc9cb6e6e8f1c0230a7775add700bc2409b (diff) | |
| download | lwn-50cdae76b8d021f31ea07af3bb30983486b79df8.tar.gz lwn-50cdae76b8d021f31ea07af3bb30983486b79df8.zip | |
docs: sysctl/kernel: document ftrace entries
Based on the ftrace documentation, the tp_printk boot parameter
documentation, and the implementation in kernel/trace/trace.c.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20200429205757.8677-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 706c2158ad25..5de73768f14e 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -265,6 +265,27 @@ domain names are in general different. For a detailed discussion see the ``hostname(1)`` man page. +ftrace_dump_on_oops +=================== + +Determines whether ``ftrace_dump()`` should be called on an oops (or +kernel panic). This will output the contents of the ftrace buffers to +the console. This is very useful for capturing traces that lead to +crashes and outputting them to a serial console. + += =================================================== +0 Disabled (default). +1 Dump buffers of all CPUs. +2 Dump the buffer of the CPU that triggered the oops. += =================================================== + + +ftrace_enabled, stack_tracer_enabled +==================================== + +See :doc:`/trace/ftrace`. + + hardlockup_all_cpu_backtrace ============================ @@ -1191,6 +1212,33 @@ If a value outside of this range is written to ``threads-max`` an ``EINVAL`` error occurs. +traceoff_on_warning +=================== + +When set, disables tracing (see :doc:`/trace/ftrace`) when a +``WARN()`` is hit. + + +tracepoint_printk +================= + +When tracepoints are sent to printk() (enabled by the ``tp_printk`` +boot parameter), this entry provides runtime control:: + + echo 0 > /proc/sys/kernel/tracepoint_printk + +will stop tracepoints from being sent to printk(), and:: + + echo 1 > /proc/sys/kernel/tracepoint_printk + +will send them to printk() again. + +This only works if the kernel was booted with ``tp_printk`` enabled. + +See :doc:`/admin-guide/kernel-parameters` and +:doc:`/trace/boottime-trace`. + + unknown_nmi_panic ================= |