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Re: Getting Linux and XP to cooperate on the BIOS clock settings

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46kmz5j02@sneakemail.com wrote:
> On 2006-10-02, Scott Reese <sreese@indianaheart.org> wrote:
>> 46kmz5j02@sneakemail.com wrote:
>>> I have a dual-boot system, running XP Pro and Debian linux.  After 
>>> switching from sarge to etch, I kept seeing a message on linux boot 
>>> about "Superblock last write time is in the future.  Fix? yes".
>>> The boot proceeds normally after that, but I don't like inexplicable 
>>> error messages, so I did some searching on the net.  Apparently, it 
>>> had something to do with my bios clock being set to local time, rather 
>>> than UTC.  The recommended "fix" was to set the bios clock to UTC, 
>>> which I did.
>>> However, when running XP, my system clock will periodically reset itself 
>>> to the hardware clock, and the time jumps ahead four hours.  This causes 
>>> problems with some audio recording I do in XP, as the program I use is 
>>> set to start at a certain time, and to split the audio file every hour.
>>> I found some articles about an XP registry key called "RealTimeIsUniversal", 
>>> and I tried that, but it didn't help.  I disabled the Windows Time Service, 
>>> since I use a third-party application to synchronize my system clock to 
>>> 0.us.pool.ntp.org a few times per day, but something is still resetting 
>>> the system time to the bios clock every so often.
>>> Is there a way I can get these two operating systems to agree on how to 
>>> set a clock?
>> Greetings:
>> In the past, it has been the case that Windows XP could not be set to
>> keep the computer's time as UTC time and do the calculations to display
>> the proper local time based on time zone.  The may have recently changed
>> that, but it would have to be post-SP2.
>> With my dual-boot laptop, I have to set Debian to use local time rather
>> than UTC time (by setting UTC=no in /etc/default/rcS), then both systems
>> keep the local clock set to the local time.
>> Using this method, I am not seeing the error messages about the write
>> time on the superblock.
>> Good Luck
>> - -Scott
> OK, I had it set for local time to begin with, and had set 
> UTC=no in /etc/default/rcS in order to get the "Superblock 
> last write time is in the future.  Fix? yes" error message to 
> go away.  I just put it back to "UTC=no", and the superblock
> error is back.
> However, I just noticed that the system "thinks" the BIOS 
> clock is set to UTC for part of the boot process, and then 
> "realizes" it is set to local time later in the boot sequence.
> Here is an excerpt from my /var/log/boot:
> Tue Oct  3 11:15:48 2006: .
> Tue Oct  3 11:15:48 2006: ^[%@Activating swap:swapon on /dev/hdc4
> Tue Oct  3 11:15:48 2006: .
> Tue Oct  3 11:15:48 2006: Will now check root file system:fsck 1.39 (29-May-2006)
> Tue Oct  3 11:15:48 2006: [/sbin/fsck.ext3 (1) -- /] fsck.ext3 -y -C0 /dev/hdc3
> Tue Oct  3 11:15:48 2006: e2fsck 1.39 (29-May-2006)
> Tue Oct  3 11:15:48 2006: Superblock last write time is in the future.  Fix? yes
> Tue Oct  3 11:15:48 2006:
> Tue Oct  3 11:15:48 2006: DEBIAN: clean, 195317/1916928 files, 1397898/3833510 blocks
> Tue Oct  3 11:15:48 2006: .
> Tue Oct  3 11:15:48 2006: Setting the system clock..
> Tue Oct  3 15:15:50 2006: System Clock set. Local time: Tue Oct  3 15:15:50 EDT 2006.
> Tue Oct  3 15:15:50 2006: Cleaning up ifupdown....
> Is there some way to move the clock setting part to earlier in the boot?


The /etc/init.d/hwclock.sh script is responsible for setting the system
clock from the bios clock at startup, and for setting the bios clock to
match the system clock at shutdown.  You might want to reboot your
Debian system and check the hardware clock before it restarts to make
sure that it is set to local time.  Then perform the same test with XP
and see if one or the other is setting the hardware clock to UTC at
shutdown.  Perhaps you made a change to the XP system that is causing it
to set the hardware clock to UTC at shutdown?

Good luck.

- -Scott
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