[dpdk-dev] [PATCH v4] 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>
---

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..05097c62d
--- /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 virtual and physical machine.
+
+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 user from the
+application selection and configuration provided by the vendor and allows user
+to customize the device through the use of packages to suit any application. For
+developers, OpenWrt is the framework to build and application without having to
+build a complete firmware around it, for users this means the ability for 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 through
+the source code, you can clone the OpenWrt source code by:
+
+.. code-block:: console
+
+	git clone https://git.openwrt.org/openwrt/openwrt.git
+
+OpenWrt configuration
+~~~~~~~~~~~~~~~~~~~~~
+
+You need to specify the Traget System & Subtarget through OpenWrt configuration,
+take x86_64 for example, you need to:
+
+* 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)``
+			   -> ``ToolChain Options``
+			   -> ``C Library implementation``
+
+Kernel configuration
+~~~~~~~~~~~~~~~~~~~~
+
+Below configurations need to 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 guide in its official site.
+
+`OpenWrt build guide
+<https://openwrt.org/docs/guide-developer/build-system/use-buildsystem>`_.
+
+After build is done, 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
+~~~~~~~~~~
+
+* meson build
+
+To cross compile with meson build, you need to write 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.
+
+* 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 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 Windows PC, you can use some free and opensource raw disk image writer program such as
+``Win32 Disk Imager`` and ``Etcher`` to write OpenWrt image (openwrt-x86-64-combined-ext4.img) to a USB
+flash driver or USB SDcard with SDcard or a Sata hard drivre or SSD from your PC.
+
+If you are using Linux, you can use old dd tool to write 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 0eaa45a76..78390fdb2 100644
--- a/doc/guides/rel_notes/release_20_02.rst
+++ b/doc/guides/rel_notes/release_20_02.rst
@@ -56,6 +56,10 @@ New Features
      Also, make sure to start the actual text at the margin.
      =========================================================
 
+* **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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2.17.1