Red Hat Linux stores parameters concerning system start up in the file /etc/sysconfig/init.
Alter the parameter BOOTUP to use terminal-independent commands to write the OK, PASSED and FAILED messages. These messages will no longer appear in green, yellow or red. The comments in /etc/sysconfig/init suggest that any value other than color will do, but it seems that BOOTUP must be set to serial.
Alter the PROMPT parameter to disallow interactive start up. Allowing an unauthenticated keystroke to stop system services is not robust against line noise and allows anyone that dials in during system boot to deny services.
Red Hat Linux runs a hardware discoverer, named kudzu. When attempting to identify a serial port Kudzu resets the serial port. This stops the serial console. Kudzu is configured from the file /etc/sysconfig/kudzu.
Kudzu can be prevented from resetting hardware by setting the configuration parameter SAFE to yes.