Time synchronization¶

Until the time synchronization is done in a more automatic way, the tools to have it running are installed as follows.

Leap second¶

The tool was provided by Dave and is used to set the leap seconds into the Linux kernel.

Steps:

Build the settai.c executable, the content of the file is the one below:

/**
 \file set-tai.c
 \brief Set tai offset in Linux kernel
 *
 *              by: John Stultz <john.stultz@linaro.org>
 *              (C) Copyright Linaro 2013
 *              Licensed under the GPLv2
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#ifdef KTEST
#include "../kselftest.h"
#else
static inline int ksft_exit_pass(void)
{
        exit(0);
}
static inline int ksft_exit_fail(void)
{
        exit(1);
}
#endif

int set_tai(int offset)
{
        struct timex tx;

        memset(&tx, 0, sizeof(tx));

        tx.modes = ADJ_TAI;
        tx.constant = offset;

        return adjtimex(&tx);
}

int get_tai(void)
{
        struct timex tx;

        memset(&tx, 0, sizeof(tx));

        adjtimex(&tx);
        return tx.tai;
}

int main(int argc, char **argv)
{
    int i, ret;

    ret = get_tai();
    printf("tai offset started at %i\n", ret);

    if (argc < 2)
    {
        printf("New offset not given, not setting\n");
    }
    else
    {
        i = strtol(argv[1],NULL,10);
        printf("Attempting to set TAI offset to %d\n",i);
        printf("Checking tai offsets can be properly set: ");
        ret = set_tai(i);
        ret = get_tai();
        if (ret != i) {
            printf("[FAILED] expected: %i got %i\n", i, ret);
            return EXIT_FAILURE;
        }
    }
    printf("[OK]\n");
    return EXIT_SUCCESS;
}

Copy the executable to /usr/local/bin/settai and make sure it is executable
cd to the init.d folder

cd /etc/init.d

Create a script named settai.

vi settai

Write the following into the script and save it

!#/bin/sh

# execute Dave tool to set the leap second to the desired value

/usr/local/bin/settai 37

Make the script executable

chmod a+x settai

Go to the rc5.d folder

cd /etc/rc5.d

Create a link to the script to be executed in the rc5 step

Links must be in rc5 for machines that have /etc/inittab with id:5:initdefault

ln -s ../init.d/settai S30settai

Check that the link works

# cat S30settai

!#/bin/sh

# execute Dave tool to set the leap second to the desiered value

/usr/local/bin/settai 37
admin@TMA-PXI:/etc/rc5.d

Chrony installation¶

Steps are:

Copy the /home/lsst/Desktop/DaveMills/chronyd-built.tgz to the PXI and unpack it.
cd to chrony-4.3
Copy chrony configuration to /etc/..

cp chrony.conf /etc/.

Add library path

export LD_LIBRARY_PATH=.

Run chrony ./chronyd

To run it as at startup:

cd to the init.d folder

cd /etc/init.d

Create a script named start_chrony.

vi start_chrony

Write the following into the script and save it

#!/bin/sh

cd /home/admin/chrony-4.3

export LD_LIBRARY_PATH=.

./chronyd

Make the script executable

chmod a+x start_chrony

Go to the rc5.d folder

cd /etc/rc5.d

Create a link to the script to be executed in the rc5 step

Links must be in rc5 for machines that have /etc/inittab with id:5:initdefault

ln -s ../init.d/start_chrony S31start_chrony

Check that the link works

admin@TMA-PXI:/etc/rc5.d# cat S31start_chrony
#!/bin/sh

cd /home/admin/chrony-4.3

export LD_LIBRARY_PATH=.

./chronyd
admin@TMA-PXI:/etc/rc5.d#