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Subject[PATCH] [man-pages] adjtimex.2: document clock_adjtime
I was experimenting with some possible changes to adjtimex(2) and
clock_adjtime(2) and tried to look up the man page to see what the
documented behavior is when I noticed that clock_adjtime() appears
to be the only system call that is currently undocumented.

Before I do any changes to it, this tries to document what I
understand it currently does.

Signed-off-by: Arnd Bergmann <>
This is my first patch to man-pages, I'm just guessing about
what should be in there and how to format it, please reword
or reformat as necessary.
man2/adjtimex.2 | 25 +++++++++++++++++++++++--
man2/clock_adjtime.2 | 1 +
2 files changed, 24 insertions(+), 2 deletions(-)
create mode 100644 man2/clock_adjtime.2

diff --git a/man2/adjtimex.2 b/man2/adjtimex.2
index fc6892d..b7c0a5f 100644
--- a/man2/adjtimex.2
+++ b/man2/adjtimex.2
@@ -35,6 +35,8 @@ adjtimex, ntp_adjtime \- tune kernel clock
.BI "int adjtimex(struct timex *" "buf" );
+.BI "int clock_adjtimex(clockid_t " clk_id, " struct timex *" "buf" );
.BI "int ntp_adjtime(struct timex *" buf );
@@ -344,6 +346,12 @@ Attempts to set read-only
.I status
bits are silently ignored.
+.SS clock_adjtime ()
+.BR clock_adjtime ()
+system call (added in Linux 2.6.39) behaves like adjtimex() but takes an additional
+.IR clk_id
+argument to specify the particular clock on which to act.
.SS ntp_adjtime ()
.BR ntp_adjtime ()
@@ -472,6 +480,11 @@ An attempt was made to set
to a value other than those listed above.
+.I clk_id
+specified is not supported on this system.
An attempt was made to set
.I buf.tick
to a value outside the range
@@ -482,6 +495,10 @@ where
is the system timer interrupt frequency.
+.I clk_id
+does not support adjustment
.I buf.modes
is neither 0 nor
@@ -503,10 +520,12 @@ T{
T} Thread safety MT-Safe
-Neither of these interfaces is described in POSIX.1
+None of these interfaces is described in POSIX.1
.BR adjtimex ()
-is Linux-specific and should not be used in programs
+.BR clock_adjtimex ()
+are Linux-specific and should not be used in programs
intended to be portable.
The preferred API for the NTP daemon is
@@ -533,6 +552,8 @@ is done by the kernel in timer context
Thus, it will take one tick into the second
for the leap second to be inserted or deleted.
+.BR clock_gettime (2)
+.BR clock_settime (2)
.BR settimeofday (2),
.BR adjtime (3),
.BR ntp_gettime (3),
diff --git a/man2/clock_adjtime.2 b/man2/clock_adjtime.2
new file mode 100644
index 0000000..b08b9c8
--- /dev/null
+++ b/man2/clock_adjtime.2
@@ -0,0 +1 @@ man2/adjtimex.2
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