doc: add aarch32 build guidance

Add cross-compiling guidance for 32-bit aarch32 DPDK on aarch64 host.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Acked-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Aaron Conole <aconole@redhat.com>

diff --git a/doc/guides/linux_gsg/cross_build_dpdk_for_arm64.rst b/doc/guides/linux_gsg/cross_build_dpdk_for_arm64.rst
index 2fa9702..d59af58 100644 (file)
--- a/doc/guides/linux_gsg/cross_build_dpdk_for_arm64.rst
+++ b/doc/guides/linux_gsg/cross_build_dpdk_for_arm64.rst
@@ -1,15 +1,17 @@
 ..  SPDX-License-Identifier: BSD-3-Clause
-    Copyright(c) 2020 ARM Corporation.
+    Copyright(c) 2021 ARM Corporation.
 
-Cross compiling DPDK for ARM64
-==============================
-This chapter describes how to cross compile DPDK for ARM64 from x86 build hosts.
+Cross compiling DPDK for aarch64 and aarch32
+============================================
+
+This chapter describes how to cross compile DPDK for aarch64 on x86 build
+machine and compile 32-bit aarch32 DPDK on aarch64 build machine.
 
 .. note::
 
-   Whilst it is recommended to natively build DPDK on ARM64 (just
-   like with x86), it is also possible to cross compile DPDK for ARM64.
-   An ARM64 cross compiler GNU toolchain or an LLVM/clang toolchain
+   Whilst it is recommended to natively build DPDK on aarch64 (just
+   like with x86), it is also possible to cross compile DPDK for aarch64.
+   An aarch64 cross compiler GNU toolchain or an LLVM/clang toolchain
    may be used for cross-compilation.
 
 
@@ -53,14 +55,18 @@ To install it in Ubuntu::
 
    sudo apt install pkg-config-aarch64-linux-gnu
 
+For aarch32, install ``pkg-config-arm-linux-gnueabihf``::
+
+   sudo apt install pkg-config-arm-linux-gnueabihf
+
 
 GNU toolchain
 -------------
 
 .. _obtain_GNU_toolchain:
 
-Obtain the cross toolchain
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+Get the cross toolchain
+~~~~~~~~~~~~~~~~~~~~~~~
 
 The latest GNU cross compiler toolchain can be downloaded from:
 https://developer.arm.com/open-source/gnu-toolchain/gnu-a/downloads.
@@ -70,21 +76,22 @@ from the page and use it to generate better code.
 As of this writing 9.2-2019.12 is the newest,
 the following description is an example of this version.
 
-.. code-block:: console
+For aarch64::
 
    wget https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz
-
-Unzip and add into the PATH
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. code-block:: console
-
    tar -xvf gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz
    export PATH=$PATH:<cross_install_dir>/gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu/bin
 
+For aarch32::
+
+   wget https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz
+   tar -xvf gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz
+   export PATH=$PATH:<cross_install_dir>/gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf/bin
+
 .. note::
 
-   For the host requirements and other info, refer to the release note section: https://releases.linaro.org/components/toolchain/binaries/
+   For the host requirements and other info, refer to the release note section:
+   https://releases.linaro.org/components/toolchain/binaries/
 
 .. _augment_the_gnu_toolchain_with_numa_support:
 
@@ -118,6 +125,10 @@ command::
    meson aarch64-build-gcc --cross-file config/arm/arm64_armv8_linux_gcc
    ninja -C aarch64-build-gcc
 
+If the target machine is aarch32 we can use the following command::
+
+   meson aarch32-build --cross-file config/arm/arm32_armv8_linux_gcc
+   ninja -C aarch32-build
 
 LLVM/Clang toolchain
 --------------------