[Git][NTPsec/ntpsec][master] More about adjtimex(2).
Eric S. Raymond
gitlab at mg.gitlab.com
Thu Sep 29 04:40:23 UTC 2016
Eric S. Raymond pushed to branch master at NTPsec / ntpsec
Commits:
5bbede64 by Eric S. Raymond at 2016-09-29T00:40:16-04:00
More about adjtimex(2).
- - - - -
1 changed file:
- devel/tour.txt
Changes:
=====================================
devel/tour.txt
=====================================
--- a/devel/tour.txt
+++ b/devel/tour.txt
@@ -195,6 +195,10 @@ kernel, whereas ntp_adjtime(2) implements clock skewing for a PLL
running in userspace (in ntpd itself). The KERNEL_PLL code can produce
much faster convergence from a cold start.
+(Confusingly, ntp_adjtime(2) can be implemented - and often is - as
+a thin userspace wrapper around adjtimex(2). The ntp_adjtime(2)
+implementation uses only a subset of adjtimex(2)'s capabilities.)
+
Deep-in-the weeds details about the kernel PLL from Hal Murray follow.
If you can follow these you may be qualified to maintain this code...
@@ -245,7 +249,7 @@ RFC 1589 covers the above timekeeping and slewing and kernel PLL.
RFC 2783 covers the API for reading a time stamp the kernel grabs when a PPS
happens.
-== Refcl ock management ==
+== Refclock management ==
There is an illuminating comment in ntpd/ntp_refclock.c that begins
"Reference clock support is provided here by maintaining the fiction
View it on GitLab: https://gitlab.com/NTPsec/ntpsec/commit/5bbede644904272606c0593f137f7abd2eeb09a6
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