Bernd-Ludwig's Website

Valid HTML 4.01 Strict Valid CSS!

Miscellaneous >> hwclock on a Thinkpad T60

hwclock on a IBM/Lenovo Thinkpad T60

This page covers an issue related to the system clock, which I came across when using Debian Linux on an IBM/Lenovo Thinkpad T60. According to what I found in the web, this issue however seems not to be limited to the combination Debian-T60, but also appears on a couple of other notebooks and with other Linux distributions. The symptoms are:

The reason for this problem is the interaction between the RTC driver and the hardware clock, which does not work properly here. However, using the additional parameter "--directisa", hwclock can be forced to use direct I/O access to the clock instead of using the RTC driver.
To force hwclock to always use this parameter, the following modification can be done (as root):

  1. Rename the file /sbin/hwclock, e.g. into /sbin/hwclock.bin
  2. Create a new file /sbin/hwclock with the following content:
    #! /bin/sh
    /sbin/hwclock.bin --directisa $*
  3. Manually execute "hwclock --hctosys", which is now working, to set the system time after the hardware clock.

That's it! Now, all described symptoms are gone and the system clock is correct.