Computer boots 2 hours after BIOS wake-up time setting (Sparky Linux)

jt1122 · 05-07-2021, 09:26 AM

Hi,

I've set the BIOS option of wake-up by time but the computer turns-on exactly 2 hours afterwards.

Both my BIOS clock & the linux clock show the same time.

I'm on sparky linux rolling (=debian testing).

I'd appreciate suggestions on this. Maybe a locale issue?.

Thanks

Turbocapitalist · 05-07-2021, 09:28 AM

Usually the hardware and the wake-up function are running on UTC. Double check what time zone you are in and the offset from UTC and then readjust the wake-up function accordingly.

jt1122 · 05-07-2021, 09:35 AM

Thanks.

But how does the BIOS know what is the current UTC time? there's no BIOS locale setting (at least in my machine) so why would there be a shift?.

Or should the BIOS time+date should always be set to UTC & the OS will adjust based on the locale?.

Turbocapitalist · 05-07-2021, 10:07 AM

(Edit: yes: the BIOS time+date should always be set to UTC & the OS will adjust based on the locale)

There is no locale setting in the hardware. That is managed by the operating system. The hardware clock itself is UTC.

In the case of GNU/Linux each of the different accounts use whichever locale they want but you can also set one to be used by default. You can even run different programs under different time zones.

Code:

date +"%F %T %Z (%z)"

date -u +"%F %T %Z (%z)"

TZ=America/Chicago date +"%F %T %Z (%z)"

TZ=Europe/Helsinki date +"%F %T %Z (%z)"

TZ=Asia/Tokyo date +"%F %T %Z (%z)"

TZ=Australia/SugganBuggan date +"%F %T %Z (%z)"

# etc

From what I remember, Windows could not manage time zones so a hack was to set the hardware to the local time. That's not appropriate on normal operating systems which can actually handle timezones.

jt1122 · 05-07-2021, 10:34 AM

Thanks

michaelk · 05-07-2021, 11:27 AM

Just as an FYI:
Your correct the BIOS or hardware clock does not have a timezone (or locale) setting and the only way the operating system (i.e. linux) knows what it is set to is via the /etc/adjtime file. The only configuration settings are UTC or LOCAL.

The system clock is always set to UTC regardless of the timezone setting and the desktop display and date command defaults to the current timezone setting to display time as local. Even though the system can adjust for either the hardware clock being UTC or local time there can be some confusion if it is set to local during daylight saving changes. This is why it is much easier to use UTC. It also helps if you are using ntp, chronyc or even systemd-timesyncd to keep the system clock set correctly.

Quote:

I've set the BIOS option of wake-up by time but the computer turns-on exactly 2 hours afterwards.

Somewhat ambiguous, does the computer wake up after two hours regardless of the actual wake time or is the difference between your local time and UTC just two hours? The BIOS wake up time is independent of the operating system.

jt1122 · 05-07-2021, 11:59 AM

Thanks.

Here's an example:
Locale time: UTC+6
BIOS currently set to locale time
The BIOS is to wake-up the machine at 08:00
In practice the computer wakes up at 14:00

The wake-up shouldn't depend on the OS clock so why does the computer wake-up 6 hours later?.

computersavvy · 05-07-2021, 10:14 PM

Quote:

Originally Posted by jt1122

Thanks.

Here's an example:
Locale time: UTC+6
BIOS currently set to locale time
The BIOS is to wake-up the machine at 08:00
In practice the computer wakes up at 14:00

The wake-up shouldn't depend on the OS clock so why does the computer wake-up 6 hours later?.

Local time UTC+6 means that local time of 1400 (2 pm) would be 08:00 (8 am) UTC. Local time in that time zone is UTC+6, so it is 6 hours ahead of UTC (or the local time clock reads 6 hours later in the day than UTC time). The wake up is happening as scheduled.

You would be ahead to turn off the bios wake up and set your wake up according to local time in the OS. Alternatively, use the bios wake up but adjust the wake up time according to the time zone difference. In your case that would mean for a local time of 8:00 am (UTC+6) the bios wake up would be 2:00 am UTC

jt1122 · 05-08-2021, 06:27 AM

What is an OS wakeup? and how can the OS turn-on the machine of it's off? nothing is running.
You might have confused wake-up with hibernate/sleep. I'm referring to a machine which is turned-off and the BIOS turns it on at the specified time.

I think I've figured out what's happening:
Both the BIOS & the OS (Sparky linux) were set to the local time.
However sparky knows that the local time is UTC+6 (for example) and resets the BIOS to its "correct" UTC time but not the BIOS wakeup time option. Therefore the next day the machine wakes up (turns-on) with a local-UTC time shift.