# Adjust time when dual booting with Windows 10 (CMOS clock set to local time)



## bertalanp99 (Jan 9, 2019)

AFAIK, FreeBSD prefers the hardware (CMOS) clock to be set to UTC, but it is possible to select that it is set to local time during the installation.

That is what I did, as I am dual booting (actually, triple) FreeBSD with Windows 10 (and Void Linux). Now the time displayed is incorrect in FreeBSD.

What is the proper way to adjust it? Shouldn't this


```
# Adjust the time zone if the CMOS clock keeps local time, as opposed to
# UTC time.  See adjkerntz(8) for details.
1,31    0-5     *       *       *       root    adjkerntz -a
```

crontab entry take care of this every half hour? My timezone has been set to CET, correctly (I live in Hungary).


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## aragats (Jan 10, 2019)

IMO, it's more logical to tell Windows that the RTC is in UTC:
	
	



```
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation]
 "RealTimeIsUniversal"=dword:00000001
```


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## SirDice (Jan 10, 2019)

bertalanp99 said:


> What is the proper way to adjust it?




```
/etc/wall_cmos_clock  Empty file.  Its presence indicates that the
                           machine's CMOS clock is set to local time, while
                           its absence indicates a UTC CMOS clock.
```
From adjkerntz(8)


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## bertalanp99 (Jan 11, 2019)

SirDice said:


> ```
> /etc/wall_cmos_clock  Empty file.  Its presence indicates that the
> machine's CMOS clock is set to local time, while
> its absence indicates a UTC CMOS clock.
> ...



That file exists on my system. The time is still incorrect :/



aragats said:


> IMO, it's more logical to tell Windows that the RTC is in UTC:
> 
> 
> 
> ...



Thank you, I guess this really is a more logical solution!


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