> -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel- > owner@xxxxxxxxxxxxxxx] On Behalf Of Thomas Gleixner > Sent: Tuesday, October 21, 2014 4:19 PM > To: Thomas Shao > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; LKML; devel@xxxxxxxxxxxxxxxxxxxxxx; > olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx; KY Srinivasan; > John Stultz; Richard Cochran > Subject: RE: [PATCH v2 1/2] timekeeping: add EXPORT_SYMBOL_GPL for > do_adjtimex() > > On Tue, 21 Oct 2014, Thomas Shao wrote: > > > I still do not have a consistent argument from you WHY you need to > > > abuse > > > do_adjtimex() to do that host - guest synchronization in the first place. > > > > > > > I need a function to gradually slew guest time. do_adjtimex() provides > > all the functionality. Also I could not find any other exposed func to > > do this. I'd like to hear any feedback from you for this. > > As Richard and others told you already, there are various options: > > 1) Use NTP on that private network, which does not involve any kernel > changes at all. > > Your argument, that this is hard for IT-Admins to set up is just > ridiculous. If an IT-Admin is not able to set that up, then he > should better stay away from setting up a guest in the first place, > really. > > 2) As pointed out already by others PPS/PTP might be a proper solution > for this. > > All it takes is a pair of timestamps (host/guest) injected into the > proper subsystem and a controlling daemon on the guest side. That > would also avoid the problem of running NTPd and your kernel side > poor mans NTPd at the same time. > > That pseudo NTP thing is just hilarious, really. > > You take the host time stamp in timesync_onchannelcallback() and > schedule work. From the work queue you correlate the host time > stamp to the current time of the guest. So you correlate time > stamps which can be an arbitrary time apart. Brilliant solution > that, really. > OK. I'll investigate these options. Thanks. > Thanks, > > tglx > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the > body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
