Hi,
Here's my patch and proposal to add a compare option to hwclock.
The idea is that it would perform similarly to adjtimex --compare.
have a nice day,
Ondrej.
>From 3a5494a1c32e2698de0508cec70149bed8149032 Mon Sep 17 00:00:00 2001
From: Ondrej Oprala <ooprala@xxxxxxxxxx>
Date: Wed, 29 Aug 2012 18:11:15 +0200
Subject: [PATCH] hwclock: add a new --compare option
The new option imitates adjtimex -c functionality and outputs
the drift in 10 second intervals.
---
sys-utils/hwclock.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 71 insertions(+), 4 deletions(-)
diff --git a/sys-utils/hwclock.c b/sys-utils/hwclock.c
index e25546d..407ac8a 100644
--- a/sys-utils/hwclock.c
+++ b/sys-utils/hwclock.c
@@ -1337,6 +1337,61 @@ manipulate_epoch(const bool getepoch,
# endif /* __alpha__ */
#endif /* __linux__ */
+/*
+ * Compare the system and CMOS time and output the drift
+ * in 10 second intervals.
+ */
+static int compare_clock (const bool utc, const bool local_opt)
+{
+ struct tm tm;
+ struct timeval tv;
+ struct adjtime adjtime;
+ double time1_sys, time2_sys;
+ time_t time1_hw, time2_hw;
+ bool hclock_valid = FALSE;
+
+ /* dummy call for increased precision */
+ gettimeofday(&tv, NULL);
+
+ if (read_adjtime(&adjtime))
+ return 1;
+ bool universal = hw_clock_is_utc(utc, local_opt, adjtime);
+ ur->get_permissions();
+
+ synchronize_to_clock_tick();
+ ur->read_hardware_clock(&tm);
+
+ gettimeofday(&tv, NULL);
+ time1_sys = tv.tv_sec + tv.tv_usec / 1000000.0;
+
+ mktime_tz(tm, universal, &hclock_valid, &time1_hw);
+
+ bool first_pass = TRUE;
+
+ while (TRUE)
+ {
+ synchronize_to_clock_tick();
+ ur->read_hardware_clock(&tm);
+
+ gettimeofday(&tv, NULL);
+ time2_sys = tv.tv_sec + tv.tv_usec / 1000000.0;
+
+ mktime_tz(tm, universal, &hclock_valid, &time2_hw);
+
+ double res = ((time1_hw - time1_sys) - (time2_hw - time2_sys))
+ / (time2_hw - time1_hw);
+
+ if(!first_pass)
+ printf ("sysclock/RTC frequency offset: %.0f ppm (%.0f ticks)\n",
+ res * 1e6, res *1e4);
+ else {
+ first_pass = FALSE;
+ printf ("sysclock/RTC frequency offset: ppm ( ticks)\n");
+ }
+ sleep(10);
+ }
+}
+
static void out_version(void)
{
printf(_("%s from %s\n"), program_invocation_short_name, PACKAGE_STRING);
@@ -1370,7 +1425,8 @@ static void usage(const char *fmt, ...)
" -w, --systohc set the hardware clock from the current system time\n"
" --systz set the system time based on the current timezone\n"
" --adjust adjust the RTC to account for systematic drift since\n"
- " the clock was last set or adjusted\n"), usageto);
+ " the clock was last set or adjusted\n"
+ " -c --compare periodically compare the system clock with the CMOS clock\n"), usageto);
#ifdef __linux__
fputs(_(" --getepoch print out the kernel's hardware clock epoch value\n"
" --setepoch set the kernel's hardware clock epoch value to the \n"
@@ -1438,7 +1494,7 @@ int main(int argc, char **argv)
/* Variables set by various options; show may also be set later */
/* The options debug, badyear and epoch_option are global */
bool show, set, systohc, hctosys, systz, adjust, getepoch, setepoch,
- predict;
+ predict, compare;
bool utc, testing, local_opt, noadjfile, directisa;
char *date_opt;
#ifdef __alpha__
@@ -1463,6 +1519,7 @@ int main(int argc, char **argv)
static const struct option longopts[] = {
{"adjust", 0, 0, 'a'},
+ {"compare", 0, 0, 'c'},
{"help", 0, 0, 'h'},
{"show", 0, 0, 'r'},
{"hctosys", 0, 0, 's'},
@@ -1540,7 +1597,7 @@ int main(int argc, char **argv)
/* Set option defaults */
show = set = systohc = hctosys = systz = adjust = noadjfile = predict =
- FALSE;
+ compare = FALSE;
getepoch = setepoch = utc = local_opt = directisa = testing = debug = FALSE;
#ifdef __alpha__
ARCconsole = Jensen = SRM = funky_toy = badyear = FALSE;
@@ -1548,7 +1605,7 @@ int main(int argc, char **argv)
date_opt = NULL;
while ((c = getopt_long(argc, argv,
- "?hvVDarsuwAJSFf:", longopts, NULL)) != -1) {
+ "?hvVDacrsuwAJSFf:", longopts, NULL)) != -1) {
err_exclusive_options(c, longopts, excl, excl_st);
@@ -1559,6 +1616,9 @@ int main(int argc, char **argv)
case 'a':
adjust = TRUE;
break;
+ case 'c':
+ compare = TRUE;
+ break;
case 'r':
show = TRUE;
break;
@@ -1733,6 +1793,13 @@ int main(int argc, char **argv)
}
}
+ if (compare) {
+ if (compare_clock(utc, local_opt))
+ hwclock_exit(EX_NOPERM);
+ else
+ hwclock_exit(EX_OK);
+ }
+
rc = manipulate_clock(show, adjust, noadjfile, set, set_time,
hctosys, systohc, systz, startup_time, utc,
local_opt, testing, predict);
--
1.7.11.4
