[U-Boot-Users] "date reset" for MPC8xx
wd at denx.de
Mon Apr 14 15:41:50 CEST 2003
in message <3E9AB4C2.6020500 at imc-berlin.de> you wrote:
> I think would should realy reset the MPC8xx's internal RTC when
> calling "date reset" or "rtc_reset" instead of "nothing to do".
But on the MPC8xx's internal RTC there is no "reset" function, so it
is IMHO appropriate to do nothing.
> Please find and consider the attached patch.
> I have seen it several times, that the MPC8xx's internal RTC contains
> an invalid date, e.g. negative times (caused by no or low battery).
There is no "invalid date" in the Unix notation of time_t. Negative
times (i. e. dates < January 1, 1970,00:00:00 UTC, are valid, too.
> That might result in dates before 1970-01-01 under Linux and that in
> turn confuses timeouts.
Oops? I am not aware of any part in U-Boot (or Linux) that uses the
system time for timeouts! And I cannot understand why January 1, 1970
should be any better than January 1, 1960 or January 1, 1950 or any
other arbitrarily chosen date.
> I've seen that udhcpc (from busybox) hangs in such cases!
FIx this, then.
> For that reason u-boot should check for valid dates and do a
> rtc_reset() if nessesary.
No. The RTC reset funtion is only to be used for RTC chips where the
hardware supports such a reset operation.
If you need a valid system time, please use the "date" command to set
a valid time.
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de
Any sufficiently advanced technology is indistinguishable from magic.
- Arthur C. Clarke
More information about the U-Boot