| Author |
Message |
Joe Smith
Guest
|
 Posted:
Mon Oct 31, 2005 5:41 am Post subject:
Re: Daylight savings change in 2007 |
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Jeff Rife wrote:
| Quote: | After looking around for a while, I think if you replace the file
"/etc/localtime" with an updated version from any Linux distribution, you
should be fine. The format for that file hasn't changed for a while, and
the GNU library functions load it at run time, so it shouldn't be hard-coded
into any app.
|
=[tivo:root]-# ls -l /lib /etc/localtime
ls: /etc/localtime: No such file or directory
total 838
-rwxr-xr-x 1 0 0 69387 May 30 2002 ld.so.1
-rwxr-xr-x 1 0 0 781535 May 30 2002 libc.so
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Chris Adams
Guest
|
| Posted:
Mon Oct 31, 2005 5:41 am Post subject:
Re: Daylight savings change in 2007 |
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|
Once upon a time, Jeff Rife <wevsr@nabs.net> said:
| Quote: | OK, then, they likely use a much older way of doing timezone stuff.
|
I wouldn't say "older", just different. Unix timezone info in
/etc/localtime (or other similar locations) predates Linux by a good
bit.
| Quote: | For standard Linux distros, there used to be a text file in /etc that held
the definitions of each timezone (similar to /etc/termcap for terminals),
but I don't recall what it was named.
|
It is /etc/localtime (on Linux), but it isn't a plain text file. Since
the data gets used a lot, the zone info text files are "compiled" into
the localtime file. See the "zic" man page for more information.
For the person with a TiVo command line: I bet if you run "date" you'll
see a UTC time. That means that the hardware clock in the TiVo doesn't
care about time zones or DST; the TiVo software accounts for it some
other way. It may even be a part of the regular data stream download,
in which case they won't even require a software update to follow the
DST change. Since some places change their time zone and DST rules,
this is something TiVo already has to handle.
For example, Indiana has always had an interesting way of handling DST.
Part of the state is in the Central time zone and part in the Eastern.
However, IIRC only the part in the Central time zone follows DST (so
half the year the state is all on the same clock, CDT and EST).
Starting in 2006, the whole state will follow DST, but some counties may
switch to a different time zone before that.
--
Chris Adams <cmadams@hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble. |
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Jeff Rife
Guest
|
| Posted:
Mon Oct 31, 2005 5:41 am Post subject:
Re: Daylight savings change in 2007 |
|
|
Joe Smith (joe@inwap.com) wrote in alt.video.ptv.tivo:
| Quote: | After looking around for a while, I think if you replace the file
"/etc/localtime" with an updated version from any Linux distribution, you
should be fine. The format for that file hasn't changed for a while, and
the GNU library functions load it at run time, so it shouldn't be hard-coded
into any app.
=[tivo:root]-# ls -l /lib /etc/localtime
ls: /etc/localtime: No such file or directory
|
OK, then, they likely use a much older way of doing timezone stuff.
For standard Linux distros, there used to be a text file in /etc that held
the definitions of each timezone (similar to /etc/termcap for terminals),
but I don't recall what it was named.
--
Jeff Rife | "But as much as everybody loves you, there is
| one question that keeps coming up...how dumb
| WAS she?"
| -- Tempus to Lois Lane |
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Stephen Harris
Guest
|
| Posted:
Mon Oct 31, 2005 6:06 pm Post subject:
Re: Daylight savings change in 2007 |
|
|
Jeff Rife <wevsr@nabs.net> wrote:
| Quote: | No, that won't work. At some point, the TiVo clock needs to jump forward or
back one hour. It knows when to do this right now, but won't do it at the
|
No. The TiVo clock never jumps forward or back an hour. The clock is
ALWAYS in UTC, pretty much like all Unix systems.
What changes is how the TiVo software _interprets_ that value and converts
it to local time, taking into account the timezone. It looks like TiVo
may have a simpler method of doing things, rather than using timezone
information, but I'm not sure. Anyway, some of the data is stored in
the MFS objects, and not on the filesystem:
# mfs_dumpobj /State/LocationConfig
LocationConfig 3497/10 PRIMARY {
Version[1]=19
PostalCode[16]=07410
AutoDetect[20]=3
TimeZoneOffset[19]=-18000
IndexPath[4]=/State/LocationConfig
}
There may be other objects in MFS which maintain the "rules" for TZ
changes. Since the MFS objects are maintained by the tivo software, it'd
be simple for a daily call to update the rules as part of the data
download.
--
Stephen Harris
usenet@spuddy.org
The truth is the truth, and opinion just opinion. But what is what?
My employer pays to ignore my opinions; you get to do it for free. |
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wkearney99
Guest
|
| Posted:
Mon Oct 31, 2005 6:42 pm Post subject:
Re: Daylight savings change in 2007 |
|
|
| Quote: | (me remembering plenty of older systems that vendors abandonded for
the last daylight savings time change 20 years ago).
|
Yes, me too. Congress has no idea how much they're going to fuck up with
this utterly stupid idea. |
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Chris Adams
Guest
|
| Posted:
Mon Oct 31, 2005 8:14 pm Post subject:
Re: Daylight savings change in 2007 |
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|
Once upon a time, Jeff Rife <wevsr@nabs.net> said:
| Quote: | No, that won't work. At some point, the TiVo clock needs to jump forward or
back one hour.
|
No it doesn't. All Unix systems keep the internal clock in UTC and
apply timezone rules to convert to local time only when needed. The
internal clock is strictly monotonically increasing; it never goes
backward and it doesn't jump forward.
I know my HD DirecTiVo clock is UTC. It has been a while since I looked
at a Series1 stand-alone, but I expect it is the same.
--
Chris Adams <cmadams@hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble. |
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GMAN
Guest
|
| Posted:
Mon Oct 31, 2005 11:24 pm Post subject:
Re: Daylight savings change in 2007 |
|
|
In article <X56dnQKJjvK4jPveRVn-pw@speakeasy.net>, "wkearney99" <wkearney99@hotmail.com> wrote:
| Quote: | (me remembering plenty of older systems that vendors abandonded for
the last daylight savings time change 20 years ago).
Yes, me too. Congress has no idea how much they're going to fuck up with
this utterly stupid idea.
If it saves just a few kids lives so that they are not walking to school in |
the freakin dark, I'm all for it. They are more important than our goddamn
electronics gear!!!! |
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Jeff Rife
Guest
|
| Posted:
Tue Nov 01, 2005 12:15 am Post subject:
Re: Daylight savings change in 2007 |
|
|
Chris Adams (cmadams@hiwaay.net) wrote in alt.video.ptv.tivo:
| Quote: | Once upon a time, Jeff Rife <wevsr@nabs.net> said:
No, that won't work. At some point, the TiVo clock needs to jump forward or
back one hour.
No it doesn't. All Unix systems keep the internal clock in UTC and
apply timezone rules to convert to local time only when needed. The
internal clock is strictly monotonically increasing; it never goes
backward and it doesn't jump forward.
|
The "jump forward" term was in reference to picking a time to record, not
an actual effect. In particular, the guide will show "3:00am" as the
timeslot after "1:30am".
As an example, if you schedule a recording for 5:00am local time, it might
record at either 0000 UTC or 0100 UTC depending on the state of daylight
savings time.
Unless the guide data has the adjustment built into it, things would break.
But, even if the guide data has the adjustment built into it, you can
record at times that don't reflect guide data (manual recordings). Unless
the clock "jumps" at the right time, some things will be missed.
As someone else pointed out, there is MFS data (instead of "Linux" data)
that might do the job, but that might just be from initial setup and have
hard-coded info that can't be updated with just a normal "guide data"
phone call.
At this point, there is now too little information to tell what is going
to happen to S1 TiVos. I don't think S2 units will have any problems, as
TiVo is committed to supporting them with new software if necessary.
--
Jeff Rife |
| http://www.nabs.net/Cartoons/OverTheHedge/BrokenInternet01.gif |
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Randy S.
Guest
|
| Posted:
Tue Nov 01, 2005 12:29 am Post subject:
Re: Daylight savings change in 2007 |
|
|
GMAN wrote:
| Quote: | In article <X56dnQKJjvK4jPveRVn-pw@speakeasy.net>, "wkearney99" <wkearney99@hotmail.com> wrote:
(me remembering plenty of older systems that vendors abandonded for
the last daylight savings time change 20 years ago).
Yes, me too. Congress has no idea how much they're going to fuck up with
this utterly stupid idea.
If it saves just a few kids lives so that they are not walking to school in
the freakin dark, I'm all for it. They are more important than our goddamn
electronics gear!!!!
|
Amen to that. Besides, any bright programmer should realize that
Daylight savings time is at the whim of the government, so needs to be
able to be easily modified. If it isn't, then shame on the programmer!
Randy S. |
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Joe Smith
Guest
|
| Posted:
Tue Nov 01, 2005 2:16 am Post subject:
Re: Daylight savings change in 2007 |
|
|
Jeff Rife wrote:
| Quote: | The "jump forward" term was in reference to picking a time to record, not
an actual effect. In particular, the guide will show "3:00am" as the
timeslot after "1:30am".
As an example, if you schedule a recording for 5:00am local time, it might
record at either 0000 UTC or 0100 UTC depending on the state of daylight
savings time.
|
Correct. But the thing you are overlooking is that even though the
request was entered using localtime, it was converted to UTC before
being stored in the To Do List. It is converted from UTC back to
localtime whenever there is a human looking at the date.
| Quote: | Unless the guide data has the adjustment built into it, things would break.
|
All the guide data is in UTC. It's the TiVo scheduler and display
routines (in To Do, Now Showing, etc) that do the adjustment.
| Quote: | But, even if the guide data has the adjustment built into it, you can
record at times that don't reflect guide data (manual recordings). Unless
the clock "jumps" at the right time, some things will be missed.
|
The clock does not jump. The times, as displayed on the To Do List,
are converted from UTC to whatever will be localtime on the date.
The scheduler keeps everything in UTC; it does not care when
daylight saving occurs.
| Quote: | As someone else pointed out, there is MFS data (instead of "Linux" data)
that might do the job, but that might just be from initial setup and have
hard-coded info that can't be updated with just a normal "guide data"
phone call.
|
No, it is not just from initial setup.
UTC is used everywhere internally.
Going through Guided Setup and changing the Time Zone setting affects
the routines that provide human readable dates.
For instance, there may be something scheduled to happen when the
epoch time is 1130789100. If the timezone is set to UTC, the
library routines will convert that to Oct 31 20:05:00 2005 when
providing human-readable display. On the other hand, if the timezone
is set to US/Pacific, those routines will convert that same number
to Oct 31 12:05 when it is displayed on screen.
-Joe |
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SINNER
Guest
|
| Posted:
Tue Nov 01, 2005 2:20 am Post subject:
Re: Daylight savings change in 2007 |
|
|
* Randy S. wrote in alt.video.ptv.tivo:
| Quote: | GMAN wrote:
In article <X56dnQKJjvK4jPveRVn-pw@speakeasy.net>, "wkearney99"
wkearney99@hotmail.com> wrote:
(me remembering plenty of older systems that vendors abandonded for
the last daylight savings time change 20 years ago).
Yes, me too. Congress has no idea how much they're going to fuck up
with this utterly stupid idea.
If it saves just a few kids lives so that they are not walking to
school in the freakin dark, I'm all for it. They are more important
than our goddamn electronics gear!!!!
Amen to that. Besides, any bright programmer should realize that
Daylight savings time is at the whim of the government, so needs to be
able to be easily modified. If it isn't, then shame on the
programmer!
|
Can you say Y2K ;)
A problem that should have been twarted years before it ever started.
--
David |
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Chris Adams
Guest
|
| Posted:
Tue Nov 01, 2005 3:05 am Post subject:
Re: Daylight savings change in 2007 |
|
|
Once upon a time, Jeff Rife <wevsr@nabs.net> said:
| Quote: | As an example, if you schedule a recording for 5:00am local time, it might
record at either 0000 UTC or 0100 UTC depending on the state of daylight
savings time.
|
All that code is already there and proven, since TiVos have been
handling DST since day 1. The only question is when the adjustment is
made.
--
Chris Adams <cmadams@hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble. |
|
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S K
Guest
|
| Posted:
Tue Nov 01, 2005 5:41 am Post subject:
Re: Daylight savings change in 2007 |
|
|
Why would it be any different than two of my three VCRs I have that auto
time set, via the info off the cable?? |
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Joe Smith
Guest
|
| Posted:
Tue Nov 01, 2005 5:41 am Post subject:
Re: Daylight savings change in 2007 |
|
|
S K wrote:
| Quote: | Why would it be any different than two of my three VCRs I have that auto
time set, via the info off the cable??
|
VCRs are set to local time as broadcast by PBS stations in your area.
VCRs have no concept of UTC; they only use localtime.
TiVo (and other Linux / Unix) systems use UTC. They have files
containing rules of how to convert from UTC to local time. These
files need to be updated before 2007 if the change becomes official.
-Joe |
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Chris Adams
Guest
|
| Posted:
Tue Nov 01, 2005 5:41 am Post subject:
Re: Daylight savings change in 2007 |
|
|
Once upon a time, Joe Smith <joe@inwap.com> said:
| Quote: | These
files need to be updated before 2007 if the change becomes official.
|
The change has already been passed into law and people are implementing
it. For example, Red Hat Enterprise Linux and Fedora Core Linux already
have updated their timezone data files with the change.
--
Chris Adams <cmadams@hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble. |
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