On Tue, Apr 07, 2015 at 11:28:40PM +0000, Keller, Jacob E wrote: > > So, I guess you want to do this because your HW has this split > > representation, but you cannot adjust the frequency? > > Several reasons: > > 1) consistency with the rest of the hardware in the driver > 2) atomic time increments (I have a patch I want to propose that will enable > atomic time increment for timecounters by just adding or subtracting from the > offset)
We have this already. See 796c1ef in v4.0-rc1. > 3) hardware may have to change the frequency of the clock driving the system > timer, so even though it was supposed to represent nominal seconds and > nanoseconds, it won't actually, since the underlying clock won't be running > at the right frequency). > 4) support the gettime64/settime64 routines via the timecounter. Of course, the big disadvantage of using timecounter is that it makes it difficult or impossible to use hardware features like periodic output signals or external time stamps. > > 32 bits of seconds gives you 136 years of uptime (assuming the counter > > starts at zero). You can just use a 64 bit mask and forget about the > > overflow, since it can never happen in practice. > > > > Ok. That's what I was thinking. I would prefer that it not happen at all, but > it really is a non-issue as you said. IMHO an uptime range of 136 years is reasonable, but you should document the actual range of possibilities according to the frequencies you mentioned. Thanks, Richard ------------------------------------------------------------------------------ BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT Develop your own process in accordance with the BPMN 2 standard Learn Process modeling best practices with Bonita BPM through live exercises http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_ source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
