Difference between revisions of "Problems with hwclock"

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(Possible solutions)
(Using the --directisa switch of hwclock(8))
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=== Using the --directisa switch of hwclock(8) ===
 
=== Using the --directisa switch of hwclock(8) ===
The '''hwclock''' command knows the parameter ''--directisa'' to access the system clock "directly" instead of accessing it by using /dev/rtc. There are several ways of doing this automatically. One is to move /sbin/hwclock (or whereever it is located on your system) to '''/sbin/hwclock.dist''' and create the following shell script, which you place at /sbin/hwclock
+
The '''hwclock''' command knows the parameter ''--directisa'' to access the system clock "directly" instead of accessing it by using /dev/rtc. There are several ways of doing this automatically.
 +
 
 +
==== Generic instructions ====
 +
Move /sbin/hwclock (or wherever it is located on your system) to '''/sbin/hwclock.dist''' and create the following shell script, which you place at /sbin/hwclock
  
 
<pre>#!/bin/sh
 
<pre>#!/bin/sh
/sbin/hwclock.dist --directisa $*</pre>
+
/sbin/hwclock.dist --directisa "$@"</pre>
 
Make the script executable (apply the same permissions you had for ''hwclock'' before) and keep your packaging system from overwriting it on updates.
 
Make the script executable (apply the same permissions you had for ''hwclock'' before) and keep your packaging system from overwriting it on updates.
  
Another way of doing this is editing the initscript of hwclock (e.g., /etc/init.d/hwclock.sh in Debian) so that "--directisa" is passed as a parameter
+
==== Debian 4.0 (etch) ====
 +
Add the following to '''/etc/default/rcS''':
 +
 
 +
<pre>HWCLOCKPARS="--directisa"</pre>
 +
 
 +
==== Debian 3.1 (sarge) and previous ====
 +
Edit '''/etc/init.d/hwclock.sh''' and change all instances of "/sbin/hwclock" to "/sbin/hwclock --directisa".
  
 
=== Compiling RTC-support into the kernel instead of as a module ===
 
=== Compiling RTC-support into the kernel instead of as a module ===

Revision as of 04:39, 23 May 2007

This page discusses the problem with /dev/rtc on certain models.

Problem description

On bootup,a message like this shows up:

select() to /dev/rtc to wait for clock tick timed out


The RTC kernel driver can't handle the system clock.

Possible solutions

Using the --directisa switch of hwclock(8)

The hwclock command knows the parameter --directisa to access the system clock "directly" instead of accessing it by using /dev/rtc. There are several ways of doing this automatically.

Generic instructions

Move /sbin/hwclock (or wherever it is located on your system) to /sbin/hwclock.dist and create the following shell script, which you place at /sbin/hwclock

#!/bin/sh
/sbin/hwclock.dist --directisa "$@"

Make the script executable (apply the same permissions you had for hwclock before) and keep your packaging system from overwriting it on updates.

Debian 4.0 (etch)

Add the following to /etc/default/rcS:

HWCLOCKPARS="--directisa"

Debian 3.1 (sarge) and previous

Edit /etc/init.d/hwclock.sh and change all instances of "/sbin/hwclock" to "/sbin/hwclock --directisa".

Compiling RTC-support into the kernel instead of as a module

Compiling RTC-support (CONFIG_RTC) into the kernel instead of compiling it as a module seems to work also. Tested on: 2.6.20.6 at Thinkpad Z61m 9450-3HG

Affected Models

Affected Operating Systems

  • Linux, all flavours. Tested with kernel 2.6.18, 2.6.19, 2.6.20.6