Re: [PATCH] FAT timezones [was Re: updating the RTC automagically]

Alexander Viro (
Sat, 20 Nov 1999 22:08:59 -0500 (EST)

On Sat, 20 Nov 1999, Peter Samuelson wrote:

> Hi Riley.
> Here's the mount option for msdos/vfat: "tzoff=N" where N == minutes
> west of UTC. Being very much a kernel-hacking newbie, I haven't
> figured out how to get "-o remount" yet. (This patch, as simple as it
> is, took me a lot longer than you'd think....)
> The idea is that mount(8) could be enhanced to detect a FAT mount,
> parse your "tzoff=PST8PDT" parameter, substitute number of minutes in
> and pass it on. Also, mount(8) could use a default "tzoff=" parameter
> with the system's or user's current time zone. (I haven't touched
> util-linux yet, but it's on my todo list.) Furthermore, when DST comes
> and goes, a cron job could remount all the FAT partitions to offset
> them by an hour. All the policy in user space....
> Alexander, what do you think of this (other than the current lack of
> "remount" support)? In my opinion, since FAT does not store absolute
> dates, the user who mounts the FS should get to decide on the time zone
> for it.

Ouch... Timezone is much nastier than just one offset. First of all, you
can't use the _current_ offset - you should take offset for the moment
of file creation. And if you expect that all timezones behave nicely...
How would you like the rules a-la "switch in the last Sunday of April and
first Sunday of October"?

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at