How to make a systemtap kernel module load persistently across reboots?

Environment

• Red Hat Enterprise Linux 6
• systemtap-runtime

Issue

• How to make a systemtap kernel module load automatically on system boot?
• Is it possible to have a systemtap kernel module load on production system without installing kernel-debuginfo and kernel-devel packages?

Resolution

• It is possible to have a systemtap kernel module load across reboots using an init service, following the below steps:

  • Follow steps in this solution to compile the systemtap script as a kernel module on a development machine and prepare production machines with systemtap-runtime package.

    • Note: development and production machines' kernels must match.

  • Copy generated systemtap module(s) to production machines.

  • Deploy the below init script on production machines as /etc/init.d/systemtap_service

    # chkconfig: 345 99 01
    # description: sample systemtap service
    
    #!/bin/bash
    
    PATH=/bin:/usr/bin:/sbin:/usr/sbin
    
    case "$1" in
    
        start)
            echo -n "Starting systemtap service"
            /sbin/insmod /root/uprobes.ko
            /usr/bin/staprun /root/systemtap_module.ko -D -o /root/systemtap_module.log
        ;;
    
        stop)
            echo -n "Stopping systemtap service"
            kill -9 `ps ax | grep "stapio" | grep -v grep | awk '{ print $1 }'`
            /sbin/rmmod systemtap_module
            /sbin/rmmod uprobes.ko
        ;;
    
        *)
        echo "Usage: /etc/init.d/systemtap_service {start|stop}"
        exit 1
        ;;
    
    esac
    
    exit 0
    

  • Change init script permissions, enable and start the service.

    # chmod 755 /etc/init.d/systemtap_service
    # chkconfig systemtap_service on
    # /etc/init.d/systemtap_service start
    

Diagnostic Steps

• Check if stapio process is running after activating the service

  # ps auxf|grep stapio
  root      2033  0.0  0.0 123632   528 ?        Ssl  17:13   0:00 /usr/libexec/systemtap/stapio -D -o /root/systemtap_module.log /root/systemtap_module.ko -F3
  

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