On Fri, 2010-08-27 at 14:03 +0200, Arnd Bergmann wrote: > On Friday 27 August 2010, Richard Cochran wrote: > > On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote: > > > On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote: > > > > On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote: > > > > > Have you considered passing a struct timex instead of ppb and ts? > > > > > > > > Yes, but the timex is not suitable, IMHO. > > > > > > Could you expand on this? > > > > We need to able to specify that the call is for a PTP clock. We could > > add that to the modes flag, like this: > > > > /*timex.h*/ > > #define ADJ_PTP_0 0x10000 > > #define ADJ_PTP_1 0x20000 > > #define ADJ_PTP_2 0x30000 > > #define ADJ_PTP_3 0x40000 > > > > I can live with this, if everyone else can, too. > > My suggestion was actually to have a new syscall with the existing > structure, and pass a clockid_t value to it, similar to your > sys_clock_adjtime(), not change the actual sys_adjtime syscall. > > > > Could we not add a adjustment mode ADJ_SETOFFSET or something that would > > > provide the instantaneous offset correction? > > > > Yes, but we would also need to add a struct timespec to the struct > > timex, in order to get nanosecond resolution. I think it would be > > possible to do in the padding at the end? > > Yes, that's exactly what the padding is for. Instead of timespec, you can > probably have a extra values for replacing the existing ppm values with > ppb values.
Right, although the ppm/ppb issue shouldn't be a problem as the timex allows for much finer then ppb resolution changes. The only adjustment to the adjtimex/timex interface that may be needed is the ability to set the time by an offset (ie: ADJ_SETOFFSET), rather then slewing the offset in (ADJ_OFFSET, or ADJ_OFFSET_SINGLESHOT). This avoids the calc offset, gettime(&now), settime(now+offset) method where any latency between the gettime and settime adds to the error. thanks -john thanks -john _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
