Issues with setting the timeofday

[Patrick Williams]

On Thu, Jul 07, 2016 at 11:32:51AM -0700, Rick Altherr wrote:
> I'm unfamiliar with Barreleye.  Does the host use the BMC as an RTC?  Are
> the commands in the first post being run on the host or on the BMC?

Rick, good questions.

On all the current Power systems, the Host does not have its own RTC.  The
skiboot code will create an RTC for the kernel by using IPMI commands down
to the BMC.  They use the standard get-sel-time / set-sel-time IPMI
command for this.  Other-BMC systems already operated this way, and since
the Host firmware support was already there for other-BMC systems, we
implemented this same behavior on openBMC.  There are also other IPMI
commands that we implemented to emulate other-BMC behavior so as to not
require Host firmware changes for openBMC.

The commands Vishwa has below here are ran from the BMC.  The commands
in the Github issue are also ran from the BMC, but you will see a call
to '/tmp/ipmitool' there.  That is a development version of the ipmitool
that will call into the dbus stack as if the Host sent an IPMI message
through the BT interface.  Thus, 'ipmitool -l dbus sel time set ...' and
'ipmitool -l dbus sel time get' are emulating the behavior of the host,
while 'date' is interacting with the BMC's kernel time subsystem.

> On Thu, Jul 7, 2016 at 11:23 AM, Patrick Williams <patrick at stwcx.xyz> wrote:
> 
> > On Thu, Jul 07, 2016 at 09:52:36AM -0700, Rick Altherr wrote:
> > > If ntpd or systemd-timesyncd is running, this makes perfect sense.  Linux
> > > maintains current time in the kernel.  The hardware RTC is only used to
> > > load an initial time at boot and is written during shutdown.  When an NTP
> > > daemon is running and an NTP server is reachable, it will adjust the
> > > kernel's current time to match NTP time.  I believe with timesyncd, it
> > > simply steps time instead of slewing like ntpd does.
> > >
> > > What are you trying to accomplish?  There is likely a way to do it if you
> > > can describe what you want to have happen.
> >
> > It looks like maybe this is related to Github issue openbmc/openbmc#310.
> >
> >     https://github.com/openbmc/openbmc/issues/310
> >
> > > On Thu, Jul 7, 2016 at 6:06 AM, Vishwanatha Subbanna <
> > vishwanath at in.ibm.com>
> > > wrote:
> > >
> > > > hey Joel,
> > > >
> > > > Here is what I am seeing on one the Barreleye box that is running
> > > > "4.4.12-openbmc-20160606-1 : kernel". I can see that time gets set but
> > > > reverts immediately. Syncing what's in hwclock does not have any effect
> > > > too. Any thoughts ?
> > > >
> > > > root at barreleye:~# date -s '2016-12-25 12:34:56' ; hwclock -w
> > > > Sun Dec 25 12:34:56 UTC 2016
> > > >
> > > > root at barreleye:~# date
> > > > Thu Jul 7 13:07:37 UTC 2016
> > > >
> > > > root at barreleye:~# hwclock -r
> > > > Sun Dec 25 12:35:01 2016 0.000000 seconds
> > > >
> > > > root at barreleye:~# hwclock -s
> > > >
> > > > root at barreleye:~# date
> > > > Thu Jul 7 13:07:52 UTC 2016
> > > > root at barreleye:~#
> > > >
> > > > Thanks
> > > >
> > > >
> > > >
> > -------------------------------------------------------------------------------------
> > > > Thanks and Regards,
> > > > Vishwanath.
> > > > Advisory Software Engineer,
> > > > Power Firmware Development,
> > > > Systems &Technology Lab,
> > > > MG2-6F-255 , Manyata Embassy Business Park,
> > > > Bangalore , KA , 560045
> > > > Ph: +91-80-46678255
> > > > E-mail: vishwanath at in.ibm.com
> > > >
> > > >
> > ----------------------------------------------------------------------------------
> > > >
> > > > _______________________________________________
> > > > openbmc mailing list
> > > > openbmc at lists.ozlabs.org
> > > > https://lists.ozlabs.org/listinfo/openbmc
> > > >
> > > >
> >
> > > _______________________________________________
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> > > openbmc at lists.ozlabs.org
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> >
> >
> > --
> > Patrick Williams
> >

-- 
Patrick Williams
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