Enabling dev_dbg prints in the kernel 3.12

Hi Bin,

Thanks for the reply.

I could see the reference document containing

<debugfs>/dynamic_debug/control. For example, if you want to enable printing from source file 'svcsock.c', line 1603 you simply do: nullarbor:~ # echo 'file svcsock.c line 1603 +p' > <debugfs>/dynamic_debug/control If you make a mistake with the syntax, the write will fail thus: nullarbor:~ # echo 'file svcsock.c wtf 1 +p' > <debugfs>/dynamic_debug/control

Where is this <debugfs> located ?

Also when I try to mount the debugfs

mount: mounting none on /sys/kernel/debug failed: Device or resource busy

is displayed.

The current directory of debug fs in my terminal is as follows

root@am335x-evm:~# ls /sys/kernel/debug/
asoc hid musb-hdrc.1.auto suspend_stats
bdi iio pinctrl ti-st
bluetooth kprobes pm_debug ubi
clk memblock pwm ubifs
dma_buf mmc0 regmap usb
extfrag mmc1 regulator wakeup_sources
gpio musb-hdrc.0.auto sleep_time

Hi Lyf,

mount: mounting none on /sys/kernel/debug failed: Device or resource busy

Where is this <debugfs> located ?

Use "mount" command to check that where "debugfs" mounted and the message seems to be debugfs got mounted already.

Hi Titus,

Consider I have the debug file system mounted at

/sys/kernel/debug/

I would like to add the debug prints for the file drivers/usb/serial/usb_serial.c

How can I do this ?

Regards,

Lyf

# echo 'file usb_serial.c =p' > /sys/kernel/debug/dynamic_debug/control