Re: /dev/rtc not working on ASUS A7V133

From: Paul Gortmaker (
Date: Wed Feb 14 2001 - 05:11:11 EST

Jan Niehusmann wrote:

> But I have a correction: The problem does not only occurr if the system
> was started automatically by the bios, a manual 'soft off/soft on' sequence
> shows the same effect. Only 'hard off/hard on' (using the switch directly
> on the power supply) seems to work every time.

Can you run the following program when things are working and then when
they are not - i.e.

cmosdump > b4
# soft off / on
cmosdump > after
diff -u b4 after

The low registers (0, & 2 IIRC) are for sec and min, so expect changes
there - but of interest will be any changes in reg 0x0a and 0x0b.


 * A quick hack to dump the CMOS RAM values from 0x0 to 0x7f. Note that
 * some CMOS are only 0x40 in size, so edit accordingly. Released to
 * the public under the terms and conditions of the Gnu General Public
 * License (GPL) included herein by reference.
 * Compile with:
 * gcc -s -N -Wall -O cmosdump.c -o cmosdump
 * Paul Gortmaker 07/95

#define CMOS_SIZE 0x80

#include <stdio.h>
#include <asm/io.h>
#include <unistd.h>
#include <errno.h>

 * <linux/rtc.h> was <linux/mc146818rtc.h> on kernels prior to 2.2.19, so
 * just define CMOS_READ/WRITE here independently and avoid the hassle.

#define RTC_PORT(x) (0x70 + (x))
#define CMOS_READ(addr) ({ \
outb_p((addr),RTC_PORT(0)); \
inb_p(RTC_PORT(1)); \
#define CMOS_WRITE(val, addr) ({ \
outb_p((addr),RTC_PORT(0)); \
outb_p((val),RTC_PORT(1)); \

void binprint (unsigned short value);

void main(void) {

unsigned short addr, val;

val= iopl(3);
if (val) {


for (addr = 0; addr < CMOS_SIZE; addr++) {
        val = CMOS_READ(addr);
        printf("0x%X:\t0x%X\t%d\t",addr, val, val);


} /*end*/

void binprint(unsigned short value) {

int bit;

for (bit=128;bit>0;bit/=2)
        printf("%s", (value & bit) ? "1" : "0");

} /* end binprint */

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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:23 EST