Quick guide to ftrace

[Chris Ball]

cjb's quick guide to kernel tracing with ftrace, as used today to
track down #9702:

mkdir /debug
mount -t debugfs debugfs /debug
cd /debug/tracing
echo function > current_tracer
echo "mmc_*" > set_ftrace_filter
echo "sdhci*" >> set_ftrace_filter
echo "sdio*" >> set_ftrace_filter
echo 1 > tracing_on
echo mem > /sys/power/state
[resume]
echo 0 > tracing_on
cat trace > /root/trace-output

-- 
Chris Ball   <cjb at laptop.org>
One Laptop Per Child