4. Compiling Linux kernel from sources

Here are the general steps to compile a Linux kernel:

4.1. Get the Linux Kernel sources

Linux kernel sources can be downloaded from

git clone https://github.com/MarvellEmbeddedProcessors/linux-marvell.git
git checkout linux-6.1.x-release

4.2. Setting up the environment

To set up the workspace for either native or cross compilation of the kernel, the installation of the following packages is required:

sudo apt-get -y install build-essential imagemagick graphviz dvipng python3-venv fonts-noto-cjk latexmk librsvg2-bin texlive-xetex flex bison libssl-dev bc

4.3. Configuring and Building Kernel

4.3.1. Cross Compilation

Cross-compiling a Linux kernel involves building the kernel on one platform (the host) for use on another platform (the target). Here are the general

4.3.1.1. Getting the toolchain

The cross-compiler toolchain is specific to the target platform. For example, to cross-compile a kernel for AArch64 on Ubuntu gcc-aarch64-linux-gnu is required.

sudo apt-get install gcc-aarch64-linux-gnu

4.3.1.2. Set environment variables

Export ARCH and CROSS_COMPILE environment variables. ARCH specifies the target architecture, and CROSS_COMPILE specifies the prefix for the cross-compile

export ARCH=arm64
export CROSS_COMPILE=aarch64-linux-gnu-

4.3.1.3. Configuring the Kernel

Use the following configuration obtained from the DAO repository to configure the kernel:

Kernel Config

cp cn10k.config <path_to_kernel_directory>/arch/arm64/configs/
cd <path_to_kernel_directory>
make ARCH=arm64 cn10k.config

Note

If above steps reports “The base file ‘.config’ does not exist. Exit.” error. As a workaround, touch .config in make kernel directory and retry the step.

This generates a .config file which can be edited if a driver needs any changes in configuration such as enabling/disabling a driver, statically built-in or loadable module of a driver into kernel.

4.3.1.4. Generating a kernel Image

make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- Image

With this, the Kernel Image is built and is located in arch/arm64/boot

4.3.1.5. Generating and installing kernel modules

make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- modules

To install modules to a specific root file system, mount the rootfs first. Then, use the INSTALL_MOD_PATH environment variable to specify the root directory of the mount point.

make modules_install INSTALL_MOD_PATH=<Path_to_rootfs_mount_point>
Eg.
   make modules_install INSTALL_MOD_PATH=/mnt/disk

4.3.2. Native Compilation

Native compilation refers to where the kernel is built directly on the target machine

4.3.2.1. Installing additional packages

Apart from the packages mentioned above, install additional packages on target

sudo apt-get -y gcc make

4.3.2.2. Configuring the Kernel

Same procedure as described in cross-compilation section

cp cn10k.config <path_to_kernel_directory>/arch/arm64/configs/
cd <path_to_kernel_directory>
make ARCH=arm64 cn10k.config

4.3.2.3. Building and install kernel modules

make ARCH=arm64 Image
make ARCH=arm64 modules
make modules_install

Kernel Image is built and located in arch/arm64/boot, while modules are installed to /lib/modules/`uname -r`

4.4. Kernel boot parameters

Some important kernel boot parameters that need to be defined before booting the kernel

vfio-pci.enable_sriov=1
rvu_af.kpu_profile=ovs_kpu_cnxk