Glenn wrote: >>>Is PPS kernel discipline compiled into the default FreeBSD kernel? >>> >>> >> >>No, but it's a pretty easy thing to turn on -- you add a line to the >>config file and tell it to go. Pretty straightforward, *once* you find >>the instructions. >> >> > > > Where would I find these instructions?
It's in the FreeBSD users manual (or whatever it's called) which I found at the FreeBSD web site. That gives general instructions for rebuilding the kernel. I'm not sure if it specifically identifies the PPS flag or not. On my 5.4 machine, it was adding: # NTP PPS support options PPS_SYNC to the /usr/src/sys/i386/config/PPS_KERNEL file, which was copied from the generic kernel config file. Then rebuild, specifying PPS_KERNEL as the config file name. There's also an associated .hints file which allows you to set the serial ports to low-latency mode by disabling the FIFO in the 16550 UART chip; this can reduce jitter. I don't recall for sure, but I *think* it's setting the second bit (ie, 0x1_) in the flags field: hint.sio.0.at="isa" hint.sio.0.port="0x3F8" hint.sio.0.flags="0x12" John _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
