lkml.org 
[lkml]   [1998]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: kernel knowledge of localtime (user-level implememntation)

I certainly agree that timesone is a mountpoint option, not a system
option. (Making the time zones loadable modules is hopefully the
obvious hack.)

i still think that the kernel knowing about the actual timezone is not
the thing to do. it looks like what you want is to somehow convert
(network) filesystems that use local time to using utc. unfortunately,
you can't. you can't even do it on a mountpoint basis as files are
what get assigned dates. it's much simpler to admit that such usage is
broken and always convert to local time from the perspective of where
you are. think about the following situation:

on a broken filesystem, write a memo in PST, switch to EST, and
then write another memo. switch back to PST and you've somehow
created a file in the future. if you think about it, that's
actually what's supposed to happen. in essence, using local time
allows us to experience time travel in the safety of our
computers and without the inconvenience of jet lag.

conceptually, switching back and forth from DST is just the same as
switching timezones. you have to go through all the same steps. if you
think of time as local time, you really do experience the gain/lose of
an hour when you do DST switching.

The problem comes that the kernel needs to be able to do bidirectional
conversion, and sometimes it gets tricky.

actually, we can solve most of the problems by just periodically
calculating a delta between the two machines concepts of local time
and using that for time conversion. that's actually what i suggested
to petr for ncpfs. if we do the same thing for smbfs, we're set. we
just need to make sure that linux' kernel concept of local time gets
updated correctly as well. that, of course, brings us back to my
initial query about where to stick periodic timezone setting.

so, where do people think a timezone updater should be stuck? do
people not like using the update daemon?

-a

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:45    [W:0.127 / U:0.316 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site