# Installation and Setup

To deploy SystemTap, you need to install the SystemTap packages along with the corresponding set of `-devel`, `-debuginfo` and `-debuginfo-common` packages for your kernel. If your system has multiple kernels installed, and you wish to use SystemTap on more than one kernel kernel, you will need to install the `-devel` and `-debuginfo` packages for each of those kernel versions.

These procedures will be discussed in detail in the following sections.

## Important

Many users confuse `-debuginfo` with `-debug`. Remember that the deployment of SystemTap requires the installation of the `-debuginfo` package of the kernel, not the `-debug` version of the kernel.

## Installing SystemTap

To deploy Systemtap, you will need to to install the following RPMs:

- `systemtap`

- `systemtap-runtime`

Assuming that `yum` is installed in the system, these two rpms can be installed with `yum install systemtap systemtap-runtime`. Note that before you can use SystemTap, you will still need to install the required kernel information RPMs.

## Installing Required Kernel Information RPMs

SystemTap needs information about the kernel in order to place instrumentation in it (i.e. probe it). This information also allows SystemTap to generate the code for the instrumentation. This information is contained in the matching `-devel`, `-debuginfo`, and `-debuginfo-common` packages for your kernel. The necessary `-devel` and `-debuginfo` packages for the ordinary "vanilla" kernel are as follows:

- `kernel-debuginfo`

- `kernel-debuginfo-common`

- `kernel-devel`

Likewise, the necessary packages for the PAE kernel would be `kernel-PAE-debuginfo`, `kernel-PAE-debuginfo-common`, and `kernel-PAE-devel`.

To determine what kernel your system is currently using, use:

    uname -r

For example, if you wish to use SystemTap on kernel version `2.6.18-53.el5` on an i686 machine, then you would need to download and install the following RPMs:

- `kernel-debuginfo-2.6.18-53.1.13.el5.i686.rpm`

- `kernel-debuginfo-common-2.6.18-53.1.13.el5.i686.rpm`

- `kernel-devel-2.6.18-53.1.13.el5.i686.rpm`

### Important

The version, variant, and architecture of the `-devel`, `-debuginfo` and `-debuginfo-common` packages must match the kernel you wish to probe with SystemTap exactly.

The easiest way to install the required kernel information packages is through `yum install` and `debuginfo-install` commands. `debuginfo-install` is included with later versions of the `yum-utils` package (for example, version 1.1.10), and also requires an appropriate `yum` repository from which to download and install `-debuginfo`/`-debuginfo-common` packages. You can install the required `-devel`, `-debuginfo`, and `-debuginfo-common` packages for your kernel.

For Red Hat Enterprise Linux 6 and newer you need the appropriate channels enabled for the system for `yum` to download and install the appropriate packages. Configure the channels with either the `rhn-channel` command or the Red Hat Network web interface. To obtain a list of the channels SystemTap needs on the system use the following script:

## rhelchannels.sh

On a system with Red Hat Enterprise Linux 6 for Workstation running the previous script would return the following list:

    rhel-x86_64-workstation-6
    rhel-x86_64-workstation-6-debuginfo
    rhel-x86_64-workstation-optional-6-debuginfo
    rhel-x86_64-workstation-optional-6

The `rhn-channel --list` will provide a list of channels the machine is currently subscribed to. If the machine is only subscribed to `rhel-x86_64-workstation-6`, then with root and Red Hat Network administrator privileges for the machine the other channels could be added with the following command:

    rhn-channel --add \
    --channel=rhel-x86_64-workstation-6-debuginfo \
    --channel=rhel-x86_64-workstation-optional-6-debuginfo \
    --channel=rhel-x86_64-workstation-optional-6

With the appropriate software repositories are enabled, install the corresponding packages for a specific kernel using `yum` with the following commands:

- `yum install `kernelname`-devel-`version``

- `debuginfo-install `kernelname`-`version``

Replace ``kernelname`` with the appropriate kernel variant name (for example, `kernel-PAE`), and ``version`` with the target kernel's version. For example, to install the required kernel information packages for the `kernel-PAE-2.6.18-53.1.13.el5` kernel, run:

- `yum install kernel-PAE-devel-2.6.18-53.1.13.el5`

- `debuginfo-install kernel-PAE-2.6.18-53.1.13.el5`

If you do not have `yum` and `yum-utils` installed (and you are unable to install them), you will have to manually download and install the required kernel information packages. To generate the URL from which to download the required packages, use the following script:

If you do not have `yum` and `yum-utils` installed (and you are unable to install them) on Red Hat Enterprise Linux 4 or 5, you will have to manually download and install the required kernel information packages. To generate the URL from which to download the required packages, use the following script:

## rheldebugurl.sh

## fedoradebugurl.sh

Once you have manually downloaded the required packages to the machine, install the RPMs by running `rpm --force -ivh `package_names``.

## Initial Testing

If you are currently using the kernel you wish to probe with SystemTap, you can immediately test whether the deployment was successful. If not, you will need to reboot and load the appropriate kernel.

To start the test, run the command `stap -v -e 'probe vfs.read {printf("read performed\n"); exit()}'`. This command simply instructs SystemTap to print `read performed` then exit properly once a virtual file system read is detected. If the SystemTap deployment was successful, you should get output similar to the following:

    Pass 1: parsed user script and 45 library script(s) in 340usr/0sys/358real ms.
    Pass 2: analyzed script: 1 probe(s), 1 function(s), 0 embed(s), 0 global(s) in 290usr/260sys/568real ms.
    Pass 3: translated to C into "/tmp/stapiArgLX/stap_e5886fa50499994e6a87aacdc43cd392_399.c" in 490usr/430sys/938real ms.
    Pass 4: compiled C into "stap_e5886fa50499994e6a87aacdc43cd392_399.ko" in 3310usr/430sys/3714real ms.
    Pass 5: starting run.
    read performed
    Pass 5: run completed in 10usr/40sys/73real ms.

The last three lines of the output (i.e. beginning with `Pass 5`) indicate that SystemTap was able to successfully create the instrumentation to probe the kernel, run the instrumentation, detect the event being probed (in this case, a virtual file system read), and execute a valid handler (print text then close it with no errors).