Module Name:	src
Committed By:	drochner
Date:		Mon Jan 18 10:50:24 UTC 1999

Modified Files:
	src/sys/arch/i386/isa: clock.c
Log Message:
Be more cautious about writing to the CMOS century byte. Update it only
if it contained a "19" before. There are machines (in particular PS/2
descendants) which have a checksum at this place.
Introduce a patchable kernel variable "rtc_update_century" to modify
the behaviour: 1="always update" (for testing and if one wants to set
the clock back) or -1="never touch".