On 12.12.2012 13:27, Mark Zhang wrote: > Hi all, > > Has anyone tried to use ftrace to debug upstream kernel? I tried today > but the result is, the serial console hung after ftrace enabled(kernel > is alive because the Magic SysRq works). > > My steps are: > - Enable CONFIG_FUNCTION_TRACER in kernel config > - Enter command: echo 0 > /sys/kernel/debug/tracing/tracing_on;echo > function > /sys/kernel/debug/tracing/current_tracer;echo 1 > > /proc/sys/kernel/ftrace_dump_on_oops > - Then sometimes the serial console hangs right after you entered the > command above, or hangs when you try to "cat /sys/kernel/debug/trace" > > I dumped some backtraces(check below, by invoking a system crash > manually) and hope it helps: I'm using ftrace to debug host1x driver + tegradrm, running on Tegra2 ventana. I just rebased them on linux-next, and I use just the events, not function tracing. echo 1 >/sys/kernel/debug/tracing/events/host1x/enable ~/drm/tests/tegra/2d/tegra_2d_tests cat /sys/kernel/debug/tracing/trace I get host1x events as expected. Also function tracing works. Terje -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
