Describe FAQ/LinuxKernelDebug101 here.

• easiest way is, as always, printk("format", ...) almost as easy is dev_info() and friends:
  • dev_info, dev_warn, dev_err, dev_dbg they do logging at the KERN_* levels (INFO, WARN, ERROR, DEBUG) respectively convenient shorthand, more readable.
  dev_dbg has additional features.

  • compiles out, unless #define DEBUG 1 is done before #include <device.h>

    • so to activate, recompile, reload
    to see them on console, lower console logging level

    • echo 8 > /proc/sys/kernel/printk