Re: [PATCH] initscripts: added save-rtc to runlevel S

[ChenQi <Qi.Chen@windriver.com>]

On 01/09/2013 01:35 PM, Felipe Ferreri Tonello wrote:
> Hi Chen,
>
> On 01/08/2013 06:16 PM, ChenQi wrote:
>> On 01/09/2013 08:18 AM, eu@felipetonello.com wrote:
>>> From: "Felipe F. Tonello" <ftonello@cercacor.com>
>>>
>>> It is necessary to add save-rtc.sh to runlevel S so the system is 
>>> updated when
>>> it boots up.
>> Hi ftonello,
>> What do you mean by "system is updated"?
> I meant system clock.
>
> What is happening now is that when you turn off the device, without 
> system halt, the next time the device is booted up the system clock is 
> not in sync with the rtc.
Hi Felipe,

I'm sorry, but I really don't see why this patch works.
Below is my understanding for the system clock, hardware clock and 
/etc/timestamp.
(The file name 'save-rtc.sh' is somewhat misleading, 'save-timestamp.sh' 
would be a more reasonable one.)

/etc/timestamp is used to provide a reasonable reference for system time.
The initial contents in this file is the building time of the image.

The system clock should always be in sync with the rtc as long as the 
/etc/init.d/hwclock.sh is present, whose main purpose is to sync system 
clock and hardware clock.
No matter whether the system is shutdown normally or crashes, the system 
clock is according to the hardware clock by hwclock.sh.

"
Also, if the value stored in /etc/timestamp is newer
[at all] than the current system time, set the system clock
from the stored value, down to the minute, not just the day.
"

To be clearer, here's a code snippet from bootmisc.sh:
"
# Set the system clock from hardware clock
# If the timestamp is more recent than the current time,
# use the timestamp instead.
test -x /etc/init.d/hwclock.sh && /etc/init.d/hwclock.sh start
if test -e /etc/timestamp
then
         SYSTEMDATE=`date -u +%4Y%2m%2d%2H%2M`
         read TIMESTAMP < /etc/timestamp
         if [ ${TIMESTAMP} -gt $SYSTEMDATE ]; then
                 date -u ${TIMESTAMP#????}${TIMESTAMP%????????}
                 test -x /etc/init.d/hwclock.sh && 
/etc/init.d/hwclock.sh stop
         fi
fi

"

Cheers,
Chen Qi

>>
>> Besides, this patch should be sent to oe-core.
> Ok.
>
> Felipe
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