Date: Sun, 28 Oct 2007 09:53:56 -0700 From: Mike Lempriere <mike@vintners.net> To: Eugene Grosbein <eugen@kuzbass.ru> Cc: Peter Jeremy <peterjeremy@optushome.com.au>, stable@freebsd.org, Ian Smith <smithi@nimnet.asn.au> Subject: Re: CMOS, daylight saving time and dual-boot Message-ID: <4724BEA4.5060500@vintners.net> In-Reply-To: <20071028160952.GA11046@svzserv.kemerovo.su> References: <20071028083955.GA69713@svzserv.kemerovo.su> <Pine.BSF.3.96.1071029005619.16091E-100000@gaia.nimnet.asn.au> <20071028160952.GA11046@svzserv.kemerovo.su>
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If you're in the US, you're a week early for the changeover -- your timezone files need to be corrected. See: http://articles.techrepublic.com.com/5100-10877_11-6163042.html Eugene Grosbein wrote: > On Mon, Oct 29, 2007 at 02:17:44AM +1100, Ian Smith wrote: > > >> > I have dual-boot machine with 7.0-BETA1 and Windows >> > that keeps CMOS time local (there is /etc/wall_cmos_clock also). >> > >> > It was tuned off yesterday evening and turned back on today, >> > loading FreeBSD. Meantime the switch from Summer Time to Standard Time >> > has ocurred. There is 'ntpd_enable="YES"' in /etc/rc.conf. >> > Nothing in a system reacted on the end of Summer Time period, >> > so ntpd just complained about 3600 seconds exceeded sanity limit >> > and bailed out (documented behavour). >> >> With standard /etc/crontab, adjkerntz -a (which catches DST changes) is >> only run between midnight and 5am, and presumably your 'today' started >> after then. >> > > Yes, really much later :-) > > >> Perhaps running that once on boot, just in case, might help >> in such circumstances? >> > > I'll test this. By the way, I cannot set local date > to '02:59:00 summer time', it sets '02:59:00 winter time' :-( > E.g., "date 200710280222.39" sets time in "KRAST" timezone > (local time is GMT+8 in summer) and "date 200710280222.40" > sets it so timezone changes to "KRAT". How could I set it > to "200710280259 KRAST"? > > >> I've done that without ntpd running, but ntpd >> -qg once on booting should handle such surprise 3600s shifts better? >> >> > There is Status Register B at the offset 0x0b in the ISA Compatible >> > CMOS its least significant bit should keep Daylight Saving flag >> > (on/off). >> >> The bit appears to be DST enable, rather than storage of current state? >> Windows date setting has a check box that I suspect reflects this bit. >> > > I don't think so, it seems that Windows keeps it's own flag > to know if it should adjust local time for daylight savings. > As you noted, FreeBSD always clears CMOS bit and > that has no affect on Windows behavour. > > >> You may find that windows will shift CMOS another hour when next booted >> too, or at least that's what I recall W98 doing to me a couple of times >> when I happened to boot it some time during some 6 month period :) >> >> > Is it used in modern hardware? Does FreeBSD use it? It is supposed to >> > use it? >> >> /sys/isa/rtc.h has >> #define RTCSB_DST 0x01 /* USA Daylight Savings Time enable */ >> >> but it's not referenced in /sys/i386/isa/clock.c (great bedtime reading) >> which is the only place that updates the RTC, AFAIK. If I'm reading it >> right, FreeBSD clears this bit during clock initialisation. >> >> (5.5-STABLE here; I haven't checked if this code has changed since) >> > > The same in CURRENT. It seems we could use this bit as storage flag :-) > I think about diskless stations that has no other storage for this. > > Eugene > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" > > > > -- Mike Lempriere- Home: mike@vintners.net Phone: 206-780-2146 Cellphone: 206-200-5902; text pager: mlemp@tmail.com
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