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AMSDK Linux User's Guide
Content is no longer maintained and is being kept for reference only!
Return to the Sitara Linux Software Developer's Guide
- 1 Overview
- 2 AMSDK 5.x and AM18x Users - READ HERE
- 3 Preparing to Build
- 4 Cleaning the Kernel Sources
- 5 Configuring the Kernel
- 6 Compiling the Kernel
- 7 Installing the Kernel
- 8 Additional Information
- 9 Archived Versions
Content is no longer maintained and is being kept for reference only!
This article will cover the basic steps for building the Linux kernel and driver modules for TI Sitara devices.
AMSDK 5.x and AM18x Users - READ HERE
Starting with Sitara Linux SDK 6.0 the location of the toolchain has changed and for non ARM 9 devices a new Linaro based toolchain will be used. Details about the change in toolchain location can be found here. Also details about the switch to Linaro can be found here.
AM18x users are not affected by the switch to Linaro. Therefore, any references to the Linaro toolchain prefix "arm-linux-gnueabihf-" should be replaced with "arm-arago-linux-gnueabi-".
For your convenience there is an archived version of these instructions for AMSDK v5.x users here.
Preparing to Build
In order to build the Linux kernel you will need a cross compiler installed on your system which can generate object code for the ARM core in your Sitara device. In the case of the AMSDK this compiler can be found inside of the SDK in the <sdk install dir>/linux-devkit/sysroots/i686-arago-linux/usr/bin directory. If you have not already done so you should add this compiler to your path by doing:
export PATH="<sdk install dir>/linux-devkit/sysroots/i686-arago-linux/usr/bin:$PATH"
Where <sdk install dir> should be replaced with the directory where the SDK was installed.
The following commands are intended to be run from the root of the kernel tree unless otherwise specified. The root of the kernel tree is the top-level directory and can be identified by looking for the "MAINTAINERS" file.
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=arm CROSS_COMPILE=arm-linux-gnueabihf- mrproper
For users who are building the kernel from within the AMSDK you can also use the Makefile at the root of the SDK installation at <sdk install dir>/Makefile to clean the kernel by doing:
cd <sdk install dir> make linux_clean
Configuring the Kernel
Before compiling the Linux kernel it needs to be configured to select what components will become part of the kernel image, which components will be build as dynamic modules, and which components will be left out all together. This is done using the Linux kernel configuration system.
Using Default Configurations
It is often easiest to start with a base default configuration and then customize it for you use case if needed. In the Linux kernel a command of the form:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- <config>
will look in the arch/arm/configs directory for the configuration file (<config> in the line above) use that file to set default configuration options. The table below shows the default configuration files for various platforms.
|Device||SDK config||PSP config|
For example, to build the default PSP configuration for the AM335x the command would be:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- am335x_evm_defconfig
To build the SDK configuration for the AM335x the command would be:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- tisdk_am335x-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 cleanup up by doing a kernel clean as mentioned above.
Customizing the Configuration
When you want to customize the kernel configuration the easiest way is to use the built in kernel configuration systems. Two of the most popular configuration systems are:
menuconfig: an ncurses based configuration utility xconfig: a Qt based graphical configuration utility.
To invoke the kernel configuration you simply use a command like:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- <config type>
i.e. for menuconfig the command would look like
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- menuconfig
whereas for xconfig the command would look like
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- xconfig
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.
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. For u-boot the kernel should be built with a u-boot header that the u-boot program can read. This is easily accomplished by using the uImage build target in the kernel. In order to build the uImage target the command is:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- uImage
This will result in a kernel image file being created in the arch/arm/boot/ directory called uImage. This file can be used by u-boot to boot your Sitara device.
If you selected any components of the kernel to be build as dynamic modules you must issue an additional command to compile those modules. The command is:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- modules
This will result in .ko (kernel object) files being placed in the kernel tree. These .ko files are the dynamic kernel modules. The next section will cover how to install these modules.
Installing the Kernel
Once the Linux kernel and modules have been compiled they must be installed. In the case of the kernel image this can be installed by copying the uImage file to the location where it is going to be read from. For example when using TFTP boot this may be the /tftpboot directory, whereas when booting from SD card this may be the first partition of the SD card.
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=arm INSTALL_MOD_PATH=<path to root of file system> modules_install
For example if you are installing the modules to an NFS share located at /home/user/targetNFS you would do:
sudo make ARCH=arm INSTALL_MOD_PATH=/home/user/targetNFS modules_install
Out-of-tree Kernel Modules
The links below provide additional information about the PSP kernel releases.
- For AM335x/Beaglebone
- For AM37x/AM3517/Beagleboard