[pups] STYX and 2.11BSD licensing

Wolfgang Helbig helbig at Informatik.BA-Stuttgart.DE
Sun Apr 8 08:10:15 AEST 2001


	
> 	Since most PDP-11s do not have a "CMOS clock" to get the date and time
> 	from I'm not sure where the kernel would get its initial date/time
> 	from. [ ... ]

In UNIX V6/V7 the kernel reads the initial time from the superblock of the
root file system. The timestamp is written each time the superblock is updated
on disk.

> 	GMT, but the other models do not - so the user/admin would have to
> 	remember to set the date/time to GMT when booting the system.

The admin just has to remember that the date(1) command converts from
localtime to GMT when setting the date -- unless an 's' is appended to
the date string. (in V6 only, not mentioned in its man page)

BTW. in V6, the timezone offset was not coded into the kernel, but
in the C-library source ctime.c. If you happen to live outside
Eastern Timezone, you'll have to change it. Furthermore the daylight
saving time switch is hardcoded in localtime() -- last Sunday in
April and last Sunday in October, with different rules for 1974
(Jan 5 and last Sunday in November) and 1975 (last Sunday in February
and last Sunday in November).

So you in V6 don't have to rebuild the kernel to adopt the timezone
changes.  Instead you have to rebuild the C-Library (at least
replace ctime.c) and build all commands that depend on it. I've
found these:

	date find ls who cron dump mail pr restore

Putting the timezone offset into the kernel like in V7 seems to be
better, because you don't have to recompile all those commands.

Wolfgang

PS. I've patches to V6, that make it y2k ready and avoid some integer
overflows in ctime, which occure since 1998, so not related
to y2k.

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