3.3.1. Users Guide¶

3.3.1.3.1. Compiler¶

Before compiling the kernel or kernel modules the SDK’s toolchain needs to be added to the PATH environment variable

export PATH=<sdk path>/linux-devkit/sysroots/x86_64-arago-linux/usr/bin:$PATH

The current compiler supported for this release along with download location can be found in the release notes for the kernel release.

3.3.1.3.2. Cleaning the Kernel Sources¶

Prior to compiling the Linux kernel it is often a good idea to make sure that the kernel sources are clean and that there are no remnants left over from a previous build.

The command to clean the kernel is:

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- distclean

3.3.1.4.1. Using Default Configurations¶

For this sdk, tisdk_[platformName]_defconfig was used to create the prebuilt files. We recommend users to use this kernel configuration (or at least use it as a starting point).

platformName is am64xx-evm for AM64x, and am65xx-evm for AM65x.

For example, to apply the default AM64x kernel configuration, use:

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- tisdk_am64xx-evm_defconfig

After the configuration step has run the full configuration file is saved to the root of the kernel tree as .config. Any further configuration changes are based on this file until it is cleaned up by doing a kernel clean as mentioned above.

If the kernel was downloaded directly from the git repository, the defconfig will need to be built with scripts. Please see ti_config_fragments/README within the kernel sources for more information. Otherwise a user will notice a significant amount of features not working.

Below is the procedure to build the defconfig from the kernel git repository.

ti_config_fragments/defconfig_builder.sh -t ti_sdk_arm64_release
export ARCH=arm64
make ti_sdk_arm64_release_defconfig
mv .config arch/arm64/configs/tisdk_[platformName]-evm_defconfig

The list of defconfig map file (i.e., ti_sdk_[device]_release used above) supported can be found from ti_config_fragments/v8_defconfig_map.txt file.

3.3.1.4.2. Customizing the Configuration¶

When you want to customize the kernel configuration the easiest way is to use the built in kernel configuration systems. One popular configuration system is menuconfig. menuconfig is an ncurses based configuration utility.

To invoke the kernel configuration you simply use a command like:

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- <config type>

i.e. for menuconfig the command would look like

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- menuconfig

Once the configuration window is open you can then select which kernel components should be included in the build. Exiting the configuration will save your selections to a file in the root of the kernel tree called .config.

3.3.1.5.1. Compiling the Kernel¶

Once the kernel has been configured it must be compiled to generate the bootable kernel image as well as any dynamic kernel modules that were selected.

By default U-boot expects Image to be the type of kernel image used.

To just build the Image use this command

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- Image

This will result in a kernel image file being created in the arch/arm64/boot/ directory called Image.

3.3.1.5.2. Compiling the Device Tree Binaries¶

Each TI evm has an unique device tree binary file required by the kernel. Therefore, you will need to build and install the correct dtb for the target device. TI device tree files are located in arch/arm64/boot/dts/ti. Below list various TI evms and the matching device tree file.

To build an individual device tree file find the name of the dts file for the board you are using and replace the .dts extension with .dtb. Then run the following command:

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- <dt filename>.dtb

The compiled device tree file with be located in arch/arm64/boot/dts/ti.

For example, the AM64x EVM device tree file is named k3-am642-evm.dts. To build the device tree binary you would run:

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- k3-am642-evm.dtb

Alternatively, you can build every device tree binary with command

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- dtbs

3.3.1.5.3. Compiling the Kernel Modules¶

By default the majority of the Linux drivers used in the sdk are not integrated into the kernel image file (Image). These drivers are built as dynamic modules. The command to build these modules is:

make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- modules

This will result in .ko (kernel object) files being placed in the kernel tree. These .ko files are the dynamic kernel modules.

3.3.1.6.1. Installing the Kernel Image and Device Tree Binaries¶

cd <kernel sources dir>
sudo cp arch/arm64/boot/Image <rootfs path>/boot
sudo cp arch/arm64/boot/dts/ti/<dt file>.dtb <rootfs path>/boot

For example, if you wanted to copy the kernel image and AM64x EVM device tree file to the rootfs partition of a SD card you would enter the below commands:

cd <kernel sources dir>
sudo cp arch/arm64/boot/Image /media/rootfs/boot
sudo cp arch/arm64/boot/dts/ti/k3-am642-evm.dtb /media/rootfs/boot

Starting with U-boot 2013.10, the kernel and device tree binaries are read from the root file system’s boot directory when booting from MMC/EMMC. (NOT from the /boot/ partition on the MMC). This would mean you copy the kernel image and device tree binaries to /media/rootfs/boot instead of /media/boot.

3.3.1.6.2. Installing the Kernel Modules¶

To install the kernel modules you use another make command similar to the others, but with an additional parameter which give the base location where the modules should be installed. This command will create a directory tree from that location like lib/modules/<kernel version> which will contain the dynamic modules corresponding to this version of the kernel. The base location should usually be the root of your target file system. The general format of the command is:

sudo make ARCH=arm64  INSTALL_MOD_PATH=<path to root of file system> modules_install

For example if you are installing the modules on the rootfs partition of the SD card you would do:

sudo make ARCH=arm64 INSTALL_MOD_PATH=/media/rootfs modules_install