On 11/21/2012 06:45:30 AM, Matthew Saltzman wrote: > On Tue, 2012-11-20 at 15:53 -0500, Tom Horsley wrote: > > On Tue, 20 Nov 2012 12:04:13 -0800 > > Geoffrey Leach wrote: > > > > > Yes it is dual-booted with Windoze. However, I have Linux running > on > > > local time for that reason. > > > > Doesn't matter. They both try to "fix" the clock the first time > they > > are booted after the DST change. There is a flag you are supposed > > to be able to set to have it not do that, but over a period of > > many years of DST changes, no flag setting I made in any version of > > Windows seemed to have any effect. > > I believe that's not quite correct. > > Linux (at least Red Hat/Fedora) saves the current time in the > hardware > clock on shutdown. If the hardware clock is set to local time, it > assumes the hardware clock is correct on boot. So if Linux is > running > at the moment the time changes, it will save the correct time. But > if > it is off at the time change, it will not correct the time on boot, > so > you have to set the hardware clock manually when you start up. If > the > hardware clock is set to UTC, then it will always set the correct > time > (according to tzdata). > > Windows doesn't touch the hardware clock while running or on shutdown > (though if it is running at the time change, the system clock will > correct itself). But it adjusts the time on the first boot after the > time change. Windows clock does have an option not to adjust for DST, > but it is set per user. > > So you get in trouble if the clock is set to local time and: > A. Linux is running at the time change and then you boot into > Windows. Then Linux updates the hardware clock on shutdown > and > Windows updates it again on boot. > B. you're not running Linux at the time change and you boot > Linux > first after the time change and forget to reset the hardware > clock. Then the time is wrong until you boot Windows. > C. you're not running Linux at the time change and you boot > Linux > next and correct the hardware clock when you start, then you > boot Windows and it corrects the clock again. > D. some subtle other failure mode I might have missed. My heavens that's complicated. However, I must confess to B above. Thanks for the analysis. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
