debug: Add runtime option to not report the debug serial port to the OS.

DOS resets the serial ports reported by the BIOS.  This can mess up
debugging and timing when the serial baud rate changes on the debug
port.  The new "etc/advertise-serial-debug-port" option allows one to
suppress the debug serial port from the normal list of serial ports
the BIOS reports to DOS.

Signed-off-by: Kevin O'Connor <>
1 file changed