On Thu, 22 Dec 2005 00:18:33 +0100 Simon Richter <Simon.Richter at hogyros.de> wrote: > A good ntpd will adjust the speed rather than write to the clock; the > ntpd shipped by most distributions can already handle multiple time sources. Yes, but there's the kernel who writes to the clock, for example http://lxr.linux.no/source/arch/arm/kernel/time.c?a=arm#L103 . > > later. The /dev/rtc interface only supports one clock. > > It can either be extended to have /dev/rtcX or we > > can extend the sysfs one to allow clock updating. > > /dev is the way to go IMO. As far as I've understood sysfs, it carries > meta information about devices and drivers only, the actual > communication then happens through device nodes still. Ok. We can use dynamic device numbers and go for the /dev interface. > > > NTP mode could then be adjusted to update one or more > > of the rtcs. Maybe each RTC could have an attribute > > (let's say /sys/class/rtc/rtcX/ntp) which tells the > > kernel whether to update it or not. > > That's entirely a userspace thing. What the userspace needs to know from > the kernel is whether the clock is writable and whether its speed can be > adjusted. agreed. there are are also some variables of interest in http://lxr.linux.no/source/include/linux/timex.h?a=arm#L188 some of them may be usefully exported in sysfs. -- Best regards, Alessandro Zummo, Tower Technologies - Turin, Italy http://www.towertech.it
