Re: [Qemu-devel] Changing RTC from UTC to local time

[Flavien]

Hello,


Bartosz Fabianowski wrote :
> 
> You can set a PC's RTC to UTC or any other time zone  for  that
> matter if you want  to.  However,  according  to  the  original
> design (dating back to the olden days of the first IBM PC), the
> RTC should be running in local time.

Just a thought :

There is a problem with setting RTC to local time  with  daylight
savings, when running multiple OSs on the same hardware.

If an OS expects RTC clock to be local, then  you'd  better  only
one OS on that system, otherwise you'll get into trouble twice  a
year. Example :
1/ Install two instances of windows on the same  machine,
2/ Only boot one of them daily for 6 months,
3/ Wait for daylight saving time, still working  with  that  same
   version of windows : It will change RTC clock and run fine.
4/ Boot the other windows : It will think "oh, I have'nt been run
   for a long time. And what happened during  that  time  ?  Time
   changed ! So, let's change RTC clock !". Your RTC  clock  will
   have been change twice.

Conclusion : setting RTC to local time is a _broken_ concept.


Flavien.