guides/freebsd_gsg/build_dpdk.rst

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.. _building_from_source:

Compiling the DPDK Target from Source
=====================================

.. note::

    Testing has been performed using FreeBSD* 10.0-RELEASE (x86_64) and requires the
    installation of the kernel sources, which should be included during the
    installation of FreeBSD*. The DPDK also requires the use of FreeBSD*
    ports to compile and function.

System Requirements
-------------------

The DPDK and its applications require the GNU make system (gmake)
to build on FreeBSD*. Optionally, gcc may also be used in place of clang
to build the DPDK, in which case it too must be installed prior to
compiling the DPDK. The installation of these tools is covered in this
section.

Compiling the DPDK requires the FreeBSD kernel sources, which should be
included during the installation of FreeBSD* on the development platform.
The DPDK also requires the use of FreeBSD* ports to compile and function.

To use the FreeBSD* ports system, it is required to update and extract the FreeBSD*
ports tree by issuing the following commands:

.. code-block:: console

    root@host:~ # portsnap fetch
    root@host:~ # portsnap extract

If the environment requires proxies for external communication, these can be set
using:

.. code-block:: console

    root@host:~ # setenv http_proxy <my_proxy_host>:<port>
    root@host:~ # setenv ftp_proxy <my_proxy_host>:<port>

The FreeBSD* ports below need to be installed prior to building the DPDK.
In general these can be installed using the following set of commands:

#.  cd /usr/ports/<port_location>

#.  make config-recursive

#.  make install

#.  make clean

Each port location can be found using:

.. code-block:: console

    user@host:~ # whereis <port_name>

The ports required and their locations are as follows:

dialog4ports
   /usr/ports/ports-mgmt/dialog4ports

GNU make(gmake)
   /usr/ports/devel/gmake

coreutils
   /usr/ports/sysutils/coreutils

For compiling and using the DPDK with gcc, it too must be installed
from the ports collection:

gcc: version 4.8 is recommended
   /usr/ports/lang/gcc48
   (Ensure that CPU_OPTS is selected (default is OFF))

When running the make config-recursive command, a dialog may be presented to the
user. For the installation of the DPDK, the default options were used.

.. note::

    To avoid multiple dialogs being presented to the user during make install,
    it is advisable before running the make install command to re-run the
    make config -recursive command until no more dialogs are seen.


Install the DPDK and Browse Sources
-----------------------------------

First, uncompress the archive and move to the DPDK source directory:

.. code-block:: console

    user@host:~ # unzip DPDK-<version>zip
    user@host:~ # cd DPDK-<version>
    user@host:~/DPDK # ls
    app/ config/ examples/ lib/ LICENSE.GPL LICENSE.LGPL Makefile mk/ scripts/ tools/

The DPDK is composed of several directories:

*   lib: Source code of DPDK libraries

*   app: Source code of DPDK applications (automatic tests)

*   examples: Source code of DPDK applications

*   config, tools, scripts, mk: Framework-related makefiles, scripts and configuration

Installation of the DPDK Target Environments
--------------------------------------------

The format of a DPDK target is:

ARCH-MACHINE-EXECENV-TOOLCHAIN

Where:

*   ARCH is:   x86_64

*   MACHINE is: native

*   EXECENV is: bsdapp

*   TOOLCHAIN is: gcc | clang

The configuration files for the DPDK targets can be found in the DPDK/config
directory in the form of:

::

    defconfig_ARCH-MACHINE-EXECENV-TOOLCHAIN

.. note::

    Configuration files are provided with the RTE_MACHINE optimization level set.
    Within the configuration files, the RTE_MACHINE configuration value is set
    to native, which means that the compiled software is tuned for the platform
    on which it is built.  For more information on this setting, and its
    possible values, see the *DPDK Programmers Guide*.

To install and make the target, use "gmake install T=<target>".

For example to compile for FreeBSD* use:

.. code-block:: console

    gmake install T=x86_64-native-bsdapp-clang

.. note::

	If the compiler binary to be used does not correspond to that given in the
	TOOLCHAIN part of the target, the compiler command may need to be explicitly
	specified. For example, if compiling for gcc, where the gcc binary is called
	gcc4.8, the command would need to be "gmake install T=<target> CC=gcc4.8".

Browsing the Installed DPDK Environment Target
----------------------------------------------

Once a target is created, it contains all the libraries and header files for the
DPDK environment that are required to build customer applications.
In addition, the test and testpmd applications are built under the build/app
directory, which may be used for testing.  A kmod directory is also present that
contains the kernel modules to install:

.. code-block:: console

    user@host:~/DPDK # ls x86_64-native-bsdapp-gcc
    app   build    hostapp    include    kmod    lib    Makefile


.. _loading_contigmem:

Loading the DPDK contigmem Module
---------------------------------

To run a DPDK application, physically contiguous memory is required.
In the absence of non-transparent superpages, the included sources for the
contigmem kernel module provides the ability to present contiguous blocks of
memory for the DPDK to use. The contigmem module must be loaded into the
running kernel before any DPDK is run.  The module is found in the kmod
sub-directory of the DPDK target directory.

The amount of physically contiguous memory along with the number of physically
contiguous blocks to be reserved by the module can be set at runtime prior to
module loading using:

.. code-block:: console

    root@host:~ # kenv hw.contigmem.num_buffers=n
    root@host:~ # kenv hw.contigmem.buffer_size=m

The kernel environment variables can also be specified during boot by placing the
following in /boot/loader.conf:

::

    hw.contigmem.num_buffers=n hw.contigmem.buffer_size=m

The variables can be inspected using the following command:

.. code-block:: console

    root@host:~ # sysctl -a hw.contigmem

Where n is the number of blocks and m is the size in bytes of each area of
contiguous memory.  A default of two buffers of size 1073741824 bytes (1 Gigabyte)
each is set during module load if they are not specified in the environment.

The module can then be loaded using kldload (assuming that the current directory
is the DPDK target directory):

.. code-block:: console

    kldload ./kmod/contigmem.ko

It is advisable to include the loading of the contigmem module during the boot
process to avoid issues with potential memory fragmentation during later system
up time.  This can be achieved by copying the module to the /boot/kernel/
directory and placing the following into /boot/loader.conf:

::

    contigmem_load="YES"

.. note::

    The contigmem_load directive should be placed after any definitions of
    hw.contigmem.num_buffers and hw.contigmem.buffer_size if the default values
    are not to be used.

An error such as:

.. code-block:: console

    kldload: can't load ./x86_64-native-bsdapp-gcc/kmod/contigmem.ko: Exec format error

is generally attributed to not having enough contiguous memory
available and can be verified via dmesg or /var/log/messages:

.. code-block:: console

    kernel: contigmalloc failed for buffer <n>

To avoid this error, reduce the number of buffers or the buffer size.

.. _loading_nic_uio:

Loading the DPDK nic_uio Module
-------------------------------

After loading the contigmem module, the nic_uio must also be loaded into the
running kernel prior to running any DPDK application.  This module must
be loaded using the kldload command as shown below (assuming that the current
directory is the DPDK target directory).

.. code-block:: console

    kldload ./kmod/nic_uio.ko

.. note::

    If the ports to be used are currently bound to a existing kernel driver
    then the hw.nic_uio.bdfs sysctl value will need to be set before loading the
    module. Setting this value is described in the next section below.

Currently loaded modules can be seen by using the "kldstat" command and a module
can be removed from the running kernel by using "kldunload <module_name>".

To load the module during boot, copy the nic_uio module to /boot/kernel
and place the following into /boot/loader.conf:

::

    nic_uio_load="YES"

.. note::

    nic_uio_load="YES" must appear after the contigmem_load directive, if it exists.

By default, the nic_uio module will take ownership of network ports if they are
recognized DPDK devices and are not owned by another module. However, since
the FreeBSD kernel includes support, either built-in, or via a separate driver
module, for most network card devices, it is likely that the ports to be used are
already bound to a driver other than nic_uio. The following sub-section describe
how to query and modify the device ownership of the ports to be used by
DPDK applications.

.. _binding_network_ports:

Binding Network Ports to the nic_uio Module
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Device ownership can be viewed using the pciconf -l command. The example below shows
four Intel® 82599 network ports under "if_ixgbe" module ownership.

.. code-block:: console

    user@host:~ # pciconf -l
    ix0@pci0:1:0:0: class=0x020000 card=0x00038086 chip=0x10fb8086 rev=0x01 hdr=0x00
    ix1@pci0:1:0:1: class=0x020000 card=0x00038086 chip=0x10fb8086 rev=0x01 hdr=0x00
    ix2@pci0:2:0:0: class=0x020000 card=0x00038086 chip=0x10fb8086 rev=0x01 hdr=0x00
    ix3@pci0:2:0:1: class=0x020000 card=0x00038086 chip=0x10fb8086 rev=0x01 hdr=0x00

The first column constitutes three components:

#.  Device name: ixN

#.  Unit name:  pci0

#.  Selector (Bus:Device:Function):   1:0:0

Where no driver is associated with a device, the device name will be none.

By default, the FreeBSD* kernel will include built-in drivers for the most common
devices; a kernel rebuild would normally be required to either remove the drivers
or configure them as loadable modules.

To avoid building a custom kernel, the nic_uio module can detach a network port
from its current device driver.  This is achieved by setting the hw.nic_uio.bdfs
kernel environment variable prior to loading nic_uio, as follows:

::

    hw.nic_uio.bdfs="b:d:f,b:d:f,..."

Where a comma separated list of selectors is set, the list must not contain any
whitespace.

For example to re-bind "ix2\@pci0:2:0:0" and "ix3\@pci0:2:0:1" to the nic_uio module
upon loading, use the following command:

.. code-block:: console

    kenv hw.nic_uio.bdfs="2:0:0,2:0:1"

The variable can also be specified during boot by placing the following into
"/boot/loader.conf", before the previously-described "nic_uio_load" line - as
shown.

::

    hw.nic_uio.bdfs="2:0:0,2:0:1"
    nic_uio_load="YES"

Binding Network Ports Back to their Original Kernel Driver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If the original driver for a network port has been compiled into the kernel,
it is necessary to reboot FreeBSD* to restore the original device binding. Before
doing so, update or remove the "hw.nic_uio.bdfs" in "/boot/loader.conf".

If rebinding to a driver that is a loadable module, the network port binding can
be reset without rebooting. To do so, unload both the target kernel module and the
nic_uio module, modify or clear the "hw.nic_uio.bdfs" kernel environment (kenv)
value, and reload the two drivers - first the original kernel driver, and then
the nic_uio driver. [The latter does not need to be reloaded unless there are
ports that are still to be bound to it].

Example commands to perform these steps are shown below:

.. code-block:: console

    kldunload nic_uio
    kldunload <original_driver>

    kenv -u hw.nic_uio.bdfs  # to clear the value completely

    kenv hw.nic_uio.bdfs="b:d:f,b:d:f,..." # to update the list of ports to bind

    kldload <original_driver>

    kldload nic_uio  # optional