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.. SPDX-License-Identifier: BSD-3-Clause
Copyright(c) 2020 ARM Corporation.
Copyright(c) 2022 StarFive
Copyright(c) 2022 SiFive
Copyright(c) 2022 Semihalf
Cross compiling DPDK for RISC-V
===============================
This chapter describes how to cross compile DPDK for RISC-V from x86 build
hosts.
.. note::
While it's possible to compile DPDK natively on a RISC-V host, it is
currently recommended to cross-compile as Linux kernel does not offer any
way for userspace to discover the vendor and architecture identifiers of the
CPU and therefore any per-chip optimization options have to be chosen via
a cross-file or ``c_args``.
Prerequisites
-------------
Ensure that you have all pre-requisites for building DPDK natively as those will
be required also for cross-compilation.
Linux kernel
~~~~~~~~~~~~
Make sure that RISC-V host is running Linux kernel 5.13 or newer. This version
introduces patches necessary for PCIe BAR mapping to userspace.
GNU toolchain
-------------
Obtain the cross toolchain
~~~~~~~~~~~~~~~~~~~~~~~~~~
The build process was tested using:
* Ubuntu toolchain (the ``crossbuild-essential-riscv64`` package).
* Latest `RISC-V GNU toolchain
<https://github.com/riscv/riscv-gnu-toolchain/releases>`_ on Ubuntu or Arch
Linux.
Alternatively the toolchain may be built straight from the source, to do that
follow the instructions on the riscv-gnu-toolchain github page.
Unzip and add into the PATH
~~~~~~~~~~~~~~~~~~~~~~~~~~~
This step is only required for the riscv-gnu-toolchain. The Ubuntu toolchain is
in the PATH already.
.. code-block:: console
tar -xvf riscv64-glibc-ubuntu-20.04-<version>.tar.gz
export PATH=$PATH:<cross_install_dir>/riscv/bin
Cross Compiling DPDK with GNU toolchain using Meson
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To cross-compile DPDK for a desired target machine use the following command::
meson setup cross-build --cross-file <target_machine_configuration>
ninja -C cross-build
For example if the target machine is a generic rv64gc RISC-V, use the following
command::
meson setup riscv64-build-gcc --cross-file config/riscv/riscv64_linux_gcc
ninja -C riscv64-build-gcc
If riscv-gnu-toolchain is used, binary names should be updated to match. Update
the following lines in the cross-file:
.. code-block:: console
[binaries]
c = 'riscv64-unknown-linux-gnu-gcc'
cpp = 'riscv64-unknown-linux-gnu-g++'
ar = 'riscv64-unknown-linux-gnu-ar'
strip = 'riscv64-unknown-linux-gnu-strip'
...
Some toolchains (such as freedom-u-sdk one) require also setting ``--sysroot``,
otherwise include paths might not be resolved. To do so, add the appropriate
paths to the cross-file:
.. code-block:: console
[properties]
...
sys_root = ['--sysroot', '<path/to/toolchain/sysroot>']
...
Supported cross-compilation targets
-----------------------------------
Currently the following targets are supported:
* Generic rv64gc ISA: ``config/riscv/riscv64_linux_gcc``
* SiFive U740 SoC: ``config/riscv/riscv64_sifive_u740_linux_gcc``
To add a new target support, ``config/riscv/meson.build`` has to be modified by
adding a new vendor/architecture id and a corresponding cross-file has to be
added to ``config/riscv`` directory.
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