[systemd-devel] [ANNOUNCE] systemd 216

Lennart Poettering lennart at poettering.net
Wed Aug 20 15:16:48 PDT 2014

On Wed, 20.08.14 21:58, Andrei Borzenkov (arvidjaar at gmail.com) wrote:

> > > I do not know how often Android users need to exchange data with
> > > Windows via USB stick, but I have to do it pretty often and it sounds
> > > like now my timestamps will be wrong. Could you please name commit that
> > > does it? The only one I can find close to it
> > > (c264aeab4b0e7b69f469e12e78d4a48b3ed7a66e) says actually
> > > 
> > > "core: only set the kernel's timezone when the RTC runs in local time"
> > > 
> > > which is quite different.
> > 
> > No, that's the one.
> > 
> Apparently fat has undocumented (at least in my copy of man page)
> option time_offset. Of course, GNOME3 does not expect users to be able
> to configure options for mounting removable devices ...

This is something we cnnot really support. I mean, as mentioned, the
kernel has no idea about DST and stuff, so how do you racefreely tell it
when the time_offset changes due to DST?

Really, we have two choices now: 

a) be "more" compatible with windows, and implement a completely broken
   scheme where we incompletely inform the kernel about timezone deltas,
   without actually being able to inform the kernel without races about
   DST. Moreover as Linux support for FAT is mostly for removable media
   instead of fixed installed ones, how are we supposed to know the
   timezone of a specific FAT device anyway?

b) be compatible with android, and consider FAT timestamps in UTC, like
   they are on all other file systems. Everything neatly makes sense,
   the DST problem goes away, the timezone ambiguity goes away. 

We voted for b).


Lennart Poettering, Red Hat

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