[dpdk-dev] [PATCH v5] doc: introduce openwrt how-to guide

[Xiaolong Ye <xiaolong.ye@intel.com>]

This doc describes how to enable DPDK on Openwrt in both virtual and
physical x86 environment.

Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
---

V5 changes:

1. improve the doc's grammar and wording according to John's
suggestions.

V4 changes:

1. add release notes

V3 changes:

1. emphasize target select in `OpenWrt configuration` section

V2 changes:

1. add meson build steps for dpdk
2. replace steps about build openwrt and running dpdk application with
links

 doc/guides/howto/index.rst             |   1 +
 doc/guides/howto/openwrt.rst           | 184 +++++++++++++++++++++++++
 doc/guides/rel_notes/release_20_02.rst |   4 +
 3 files changed, 189 insertions(+)
 create mode 100644 doc/guides/howto/openwrt.rst

diff --git a/doc/guides/howto/index.rst b/doc/guides/howto/index.rst
index a4c131652..5a97ea508 100644
--- a/doc/guides/howto/index.rst
+++ b/doc/guides/howto/index.rst
@@ -19,3 +19,4 @@ HowTo Guides
     packet_capture_framework
     telemetry
     debug_troubleshoot
+    openwrt
diff --git a/doc/guides/howto/openwrt.rst b/doc/guides/howto/openwrt.rst
new file mode 100644
index 000000000..fceab1b91
--- /dev/null
+++ b/doc/guides/howto/openwrt.rst
@@ -0,0 +1,184 @@
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2019 Intel Corporation.
+
+Enable DPDK on openwrt
+======================
+
+This document describes how to enable Data Plane Development Kit (DPDK) on
+Openwrt in both a virtual and physical x86 environment.
+
+Introduction
+------------
+
+The OpenWrt project is a Linux operating system targeting embedded devices.
+Instead of trying to create a single, static firmware, OpenWrt provides a fully
+writable filesystem with package management. This frees the user from the
+application selection and configuration provided by the vendor and allows users
+to customize the device through the use of packages to suit any application. For
+developers OpenWrt is the framework to build an application without having to
+build a complete firmware around it. For users is offers full customization
+to use the device in ways never envisioned.
+
+Pre-requisites
+~~~~~~~~~~~~~~
+
+You need gcc, binutils, bzip2, flex, python3.5+, perl, make, find, grep, diff,
+unzip, gawk, getopt, subversion, libz-dev and libc headers installed.
+
+Build OpenWrt
+-------------
+
+You can obtain OpenWrt image through https://downloads.openwrt.org/releases. To
+fully customize your own OpenWrt, it is highly recommended to build it from
+the source code. You can clone the OpenWrt source code as follows:
+
+.. code-block:: console
+
+    git clone https://git.openwrt.org/openwrt/openwrt.git
+
+OpenWrt configuration
+~~~~~~~~~~~~~~~~~~~~~
+
+* Select ``x86`` in ``Target System``
+* Select ``x86_64`` in ``Subtarget``
+* Select ``Build the OpenWrt SDK`` for cross-compilation environment
+* Select ``Use glibc`` in ``Advanced configuration options (for developers)``
+  then ``ToolChain Options`` and ``C Library implementation``
+
+Kernel configuration
+~~~~~~~~~~~~~~~~~~~~
+
+The following configurations should be enabled:
+
+* ``CONFIG_UIO=y``
+* ``CONFIG_HUGETLBFS=y``
+* ``CONFIG_HUGETLB_PAGE=y``
+* ``CONFIG_PAGE_MONITOR=y``
+
+Build steps
+~~~~~~~~~~~
+
+For detailed OpenWrt build steps, please refer to the
+`OpenWrt build guide
+<https://openwrt.org/docs/guide-developer/build-system/use-buildsystem>`_.
+
+After the build is completed, you can find the images and sdk in
+``<OpenWrt Root>/bin/targets/x86/64-glibc/``.
+
+
+DPDK Cross Compilation for OpenWrt
+----------------------------------
+
+Pre-requisites
+~~~~~~~~~~~~~~
+
+NUMA is required to run DPDK in x86.
+
+.. note::
+
+    For compiling the NUMA lib, run ``libtool --version`` to ensure the libtool
+    version >= 2.2, otherwise the compilation will fail with errors.
+
+.. code-block:: console
+
+    git clone https://github.com/numactl/numactl.git
+    cd numactl
+    git checkout v2.0.13 -b v2.0.13
+    ./autogen.sh
+    autoconf -i
+    export PATH=<OpenWrt sdk>/glibc/openwrt-sdk-x86-64_gcc-8.3.0_glibc.Linux-x86_64/staging_dir/toolchain-x86_64_gcc-8.3.0_glibc/bin/:$PATH
+    ./configure CC=x86_64-openwrt-linux-gnu-gcc --prefix=<OpenWrt SDK toolchain dir>
+    make install
+
+The numa header files and lib file is generated in the include and lib folder
+respectively under <OpenWrt SDK toolchain dir>.
+
+Build DPDK
+~~~~~~~~~~
+
+To cross compile with meson build, you need to write a customized cross file
+first.
+
+.. code-block:: console
+
+    [binaries]
+    c = 'x86_64-openwrt-linux-gcc'
+    cpp = 'x86_64-openwrt-linux-cpp'
+    ar = 'x86_64-openwrt-linux-ar'
+    strip = 'x86_64-openwrt-linux-strip'
+
+    meson builddir --cross-file openwrt-cross
+    ninja -C builddir
+
+.. note::
+
+    For compiling the igb_uio with the kernel version used in target machine,
+    you need to explicitly specify kernel_dir in meson_options.txt.
+
+To cross compile with make:
+
+.. code-block:: console
+
+    export STAGING_DIR=<OpenWrt sdk>/glibc/openwrt-sdk-x86-64_gcc-8.3.0_glibc.Linux-x86_64/staging_dir
+    export RTE_SDK=`pwd`
+    export RTE_KERNELDIR=<OpenWrt Root>/build_dir/target-x86_64_glibc/linux-x86_64/linux-4.19.81/
+    make config T=x86_64-native-linuxapp-gcc
+    make -j 100 CROSS=x86_64-openwrt-linux-gnu-
+
+Running DPDK application on OpenWrt
+-----------------------------------
+
+Virtual machine
+~~~~~~~~~~~~~~~
+
+* Extract the boot image
+
+.. code-block:: console
+
+    gzip -d openwrt-x86-64-combined-ext4.img.gz
+
+* Launch Qemu
+
+.. code-block:: console
+
+    qemu-system-x86_64 \
+            -cpu host \
+            -smp 8 \
+            -enable-kvm \
+            -M q35 \
+            -m 2048M \
+            -object memory-backend-file,id=mem,size=2048M,mem-path=/tmp/hugepages,share=on \
+            -drive file=<Your OpenWrt images folder>/openwrt-x86-64-combined-ext4.img,id=d0,if=none,bus=0,unit=0 \
+            -device ide-hd,drive=d0,bus=ide.0 \
+            -net nic,vlan=0 \
+            -net nic,vlan=1 \
+            -net user,vlan=1 \
+            -display none \
+
+
+Physical machine
+~~~~~~~~~~~~~~~~
+
+If you are using a Windows PC, you can use an image writer application such as
+``Win32 Disk Imager`` and ``Etcher`` to write the OpenWrt image
+(openwrt-x86-64-combined-ext4.img) to a USB flash driver or SDcard.
+
+If you are using Linux, you can use the ``dd`` tool to write the OpenWrt image
+to the drive you want to write the image on.
+
+.. code-block:: console
+
+    dd if=openwrt-18.06.1-x86-64-combined-squashfs.img of=/dev/sdX
+
+Where sdX is name of the drive. (You can find it though ``fdisk -l``)
+
+Running DPDK
+~~~~~~~~~~~~
+
+More detailed info about how to run a DPDK application please refer to
+``Running DPDK Applications`` section of :ref:`the DPDK documentation <linux_gsg>`.
+
+.. note::
+
+    You need to install pre-built numa libraries (including soft link)
+    to /usr/lib64 in OpenWrt.
diff --git a/doc/guides/rel_notes/release_20_02.rst b/doc/guides/rel_notes/release_20_02.rst
index 08f571268..9e1e0dd89 100644
--- a/doc/guides/rel_notes/release_20_02.rst
+++ b/doc/guides/rel_notes/release_20_02.rst
@@ -116,6 +116,10 @@ New Features
 
   Added support for ESP rte_flow patterns to the testpmd application.
 
+* **Added OpenWrt howto guide.**
+
+  Added document describes how to enable DPDK on OpenWrt in both virtual and
+  physical machine.
 
 Removed Items
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