Kgdb supports using the gdb serial protocol to send console messages to the debugger when the debugger is connected and running. There are two ways to activate this feature.
Activate with the kernel command line option:
kgdbcon
Use sysfs before configuring an io driver
echo 1 > /sys/module/kgdb/parameters/kgdb_use_con
NOTE: If you do this after you configure the kgdb I/O driver, the setting will not take effect until the next point the I/O is reconfigured.
IMPORTANT NOTE: Using this option with kgdb over the console (kgdboc) or kgdb over ethernet (kgdboe) is not supported.