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Be more cautious about writing to the CMOS century byte. Update it only

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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".
This commit is contained in:
drochner 1999-01-18 10:50:23 +00:00
parent d170a5e781
commit 67589898ca
1 changed files with 16 additions and 6 deletions
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22
sys/arch/i386/isa/clock.c
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@ -1,4 +1,4 @@
/* $NetBSD: clock.c,v 1.55 1998/10/13 15:14:13 perry Exp $ */
/* $NetBSD: clock.c,v 1.56 1999/01/18 10:50:23 drochner Exp $ */
/*-
* Copyright (c) 1993, 1994 Charles M. Hannum.
@ -488,6 +488,14 @@ bintobcd(n)
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.
@ -539,16 +547,17 @@ inittodr(base)
century, yr);
/* Kludge to roll over century. */
if ((century == 19) && (tcentury == 20) && (yr == 00)) {
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 {
printf("WARNING: CHECK AND RESET THE DATE!\n");
}
}
} else if (century == 19 && rtc_update_century == 0)
rtc_update_century = 1; /* will update later in resettodr() */
yr = (tcentury == 20) ? yr+100 : yr;
/*
@ -654,7 +663,8 @@ resettodr()
s = splclock();
rtcput(&rtclk);
mc146818_write(NULL, NVRAM_CENTURY, century); /* XXX softc */
if (rtc_update_century > 0)
mc146818_write(NULL, NVRAM_CENTURY, century); /* XXX softc */
splx(s);
}