Live CD changes BIOS clock

Bug #497504 reported by Thomas Blankenhorn on 2009-12-16
This bug affects 3 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

I use a laptop that usually runs Windows XP. To try out Ubuntu 9.10 on it, I booted Ubuntu from the Live CD, selecting the boot screen's menu item "Try Ubuntu without any change to your computer". Ubuntu booted up; I played around with it for a while; everything went fine so far. Although Ubuntu's clock was set to different time than Windows' -- GMT I guess -- that was no problem for the purpose of trying it out.

The problem appeared when I shut down Ubuntu and rebooted into Windows: The system clock still showed the time to which Ubuntu had changed it. I had to correct it by updating Windows' system time. Ubuntu had changed the computer's BIOS clock.

Now, I admit that from a narrowly technical point of view, this bug in itself isn't a big deal. After all, it's almost trivial to work around. Nevertheless, it _is_ a serious problem for me that this behaviour breaks the deal Ubuntu had offered me before I booted it: "Try Ubuntu _without_any_change_ to your computer". If you tell me you won't touch my computer, and then go ahead and change its BIOS clock anyway, how I can I trust that you haven't changed anything else?

Best regards,


ProblemType: Bug
Architecture: i386
Date: Wed Dec 16 17:50:45 2009
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/bin/yelp
LiveMediaBuild: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
Package: yelp 2.28.0-0ubuntu2
ProcVersionSignature: Ubuntu 2.6.31-14.48-generic
SourcePackage: yelp
Uname: Linux 2.6.31-14-generic i686
 (gnome-settings-daemon:3343): GLib-CRITICAL **: g_propagate_error: assertion `src != NULL' failed
 (gnome-settings-daemon:3343): GLib-CRITICAL **: g_propagate_error: assertion `src != NULL' failed
 (nautilus:3389): Eel-CRITICAL **: eel_preferences_get_boolean: assertion `preferences_is_initialized ()' failed
 (polkit-gnome-authentication-agent-1:3420): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed
 (yelp:3561): Yelp-WARNING **: Failed to load config file: No such file or directory

Sam (slappyfrogg) wrote :

Same experiment with a LiveCD created from the latest download this evening.

I agree with Thomas that if one promises not to touch a user's computer, one should not touch a user's computer.

Sabra (sglato) on 2010-01-01
affects: ubuntu → linux (Ubuntu)
Andy Whitcroft (apw) on 2010-01-13
tags: added: karmic
Alex Sims (alex-softgrow) wrote : suggests that altering /etc/default/rcS would resolve this problem for a Live CD.

Changing from UTC=yes to UTC=no would mean that the BIOS time would be treated as local time rather than UTC time.

The difference is the way Ubuntu Linux and Windows handle time, Windows considers the BIOS clock of the computer to be the local time where as Ubuntu considers it as UTC time. To solve this we would have to set Ubuntu Linux to consider the hardware or BIOS clock as local time

This may be a possible solution but then the timezone would need to be set somehow for LiveCD use.

Jeremy Foshee (jeremyfoshee) wrote :

Hi Thomas,

This bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? Can you try with the latest development release of Ubuntu? ISO CD images are available from .

If it remains an issue, could you run the following command from a Terminal (Applications->Accessories->Terminal). It will automatically gather and attach updated debug information to this report.

apport-collect -p linux 497504

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text. Please let us know your results.

Thanks in advance.

    [This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]

tags: added: needs-kernel-logs
tags: added: needs-upstream-testing
tags: added: kj-triage
Changed in linux (Ubuntu):
status: New → Incomplete

Today I re-tested with the Ubuntu 10.04 Live DVD. The bug is gone, as far as I am concerned.

Jeremy, about testing the upstream kernel: While I'm willing to do that, I'm not quite sure what would constitute an acceptable test for you, considering that this bug occurred on a Live CD. Would I have to create a modified Live CD that uses Linus's most recent kernel instead of Ubuntu's? If so, can you give me a pointer on how to do that?

Jeremy Foshee (jeremyfoshee) wrote :

Hi Thomas,
    You are right, that doesn't seem helpful. Unfortunately the script that comments on bugs as me doesn't have a way to handle that as it is more broadly focused. Thanks for your testing. Are you satisfied that this is fixed?



Jeremy Foshee (jeremyfoshee) wrote :

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu release . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]

tags: added: kj-expired
Changed in linux (Ubuntu):
status: Incomplete → Expired
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