unable to set time very far in the future

[Jan Schaumann <jschauma%netmeister.org@localhost>]

Hey,

I just noticed that I'm unable to set my system clock
to date beyond 4147-08-20T07:32:16:

 # date 414708200732.16; date +%s
 Sun Aug 20 07:32:16 UTC 4147
 68719476736
 # date 414708200732.17
 date: settimeofday: Invalid argument

With a tv_sec value of 68719476737 well below any max
for the time_t data type, it seems as if there is
another limitation somewhere in the kernel, but which
one?

We're certainly able to _represent_ larger dates up
until the 32-bit limitation of the tm_year:

$ date -r 67768036191676799
Wed Dec 31 23:59:59 UTC 2147485547

- I just can't _set_ the clock to any value above
68719476736.  Anybody know why?

-Jan