[NVRAM century at nonstandard place]

perry@piermont.com said:
> Is there any way we could *detect* this sort of PS/2 descended BIOS?
> If not...  

Perhaps check for a PS-2 stule checksum... but there is no
guarantee that other BIOSes make trouble too.

What do you think about the following?

best regards
Matthias


Index: clock.c
===================================================================
RCS file: /cvsroot/src/sys/arch/i386/isa/clock.c,v
retrieving revision 1.55
diff -c -r1.55 clock.c
*** clock.c	1998/10/13 15:14:13	1.55
--- clock.c	1999/01/11 12:17:27
***************
*** 489,494 ****
--- 489,502 ----
  static int timeset;
  
  /*
+  * patchable to control century byte handling:
+  * 1: always update in resettodr()
+  * -1: never touch
+  * 0: try to figure out itself
+  */
+ int rtc_update_century = 0;
+ 
+ /*
   * Initialize the time of day register, based on the time base which is, e.g.
   * from a filesystem.
   */
***************
*** 539,554 ****
  		    century, yr);
  
  		/* Kludge to roll over century. */
! 		if ((century == 19) && (tcentury == 20) && (yr == 00)) {
  			printf("WARNING: Setting NVRAM century to 20\n");
  			s = splclock();
  			/* note: 0x20 = 20 in BCD. */
  			mc146818_write(NULL, NVRAM_CENTURY, 0x20); /*XXXsoftc*/
  			splx(s);
- 		} else {
- 			printf("WARNING: CHECK AND RESET THE DATE!\n");
  		}
! 	}
  	yr = (tcentury == 20) ? yr+100 : yr;
   
  	/*
--- 547,563 ----
  		    century, yr);
  
  		/* Kludge to roll over century. */
! 		if ((century == 19) && (tcentury == 20) && (yr == 00) &&
! 			rtc_update_century >= 0) {
  			printf("WARNING: Setting NVRAM century to 20\n");
  			s = splclock();
  			/* note: 0x20 = 20 in BCD. */
  			mc146818_write(NULL, NVRAM_CENTURY, 0x20); /*XXXsoftc*/
  			splx(s);
  		}
! 	} else if (century == 19 && rtc_update_century == 0)
! 		rtc_update_century = 1; /* will update later in resettodr() */
! 
  	yr = (tcentury == 20) ? yr+100 : yr;
   
  	/*
***************
*** 654,660 ****
  
  	s = splclock();
  	rtcput(&rtclk);
! 	mc146818_write(NULL, NVRAM_CENTURY, century); /* XXX softc */
  	splx(s);
  }
  
--- 663,670 ----
  
  	s = splclock();
  	rtcput(&rtclk);
! 	if (rtc_update_century > 0)
! 		mc146818_write(NULL, NVRAM_CENTURY, century); /* XXX softc */
  	splx(s);
  }