3 Using the Standard SDK

This chapter describes the standard SDK and how to install it. Information includes unique installation and setup aspects for the standard SDK.

Note

For a side-by-side comparison of main features supported for a standard SDK as compared to an extensible SDK, see the “Introduction” section.

You can use a standard SDK to work on Makefile and Autotools-based projects. See the “Using the SDK Toolchain Directly” chapter for more information.

3.1 Why use the Standard SDK and What is in It?

The Standard SDK provides a cross-development toolchain and libraries tailored to the contents of a specific image. You would use the Standard SDK if you want a more traditional toolchain experience as compared to the extensible SDK, which provides an internal build system and the devtool functionality.

The installed Standard SDK consists of several files and directories. Basically, it contains an SDK environment setup script, some configuration files, and host and target root filesystems to support usage. You can see the directory structure in the “Installed Standard SDK Directory Structure” section.

3.2 Installing the SDK

The first thing you need to do is install the SDK on your Build Host by running the *.sh installation script.

You can download a tarball installer, which includes the pre-built toolchain, the runqemu script, and support files from the appropriate toolchain directory within the Index of Releases. Toolchains are available for several 32-bit and 64-bit architectures with the x86_64 directories, respectively. The toolchains the Yocto Project provides are based off the core-image-sato and core-image-minimal images and contain libraries appropriate for developing against the corresponding image.

The names of the tarball installer scripts are such that a string representing the host system appears first in the filename and then is immediately followed by a string representing the target architecture:

poky-glibc-host_system-image_type-arch-toolchain-release_version.sh

Where:
    host_system is a string representing your development system:

               i686 or x86_64.

    image_type is the image for which the SDK was built:

               core-image-minimal or core-image-sato.

    arch is a string representing the tuned target architecture:

               aarch64, armv5e, core2-64, i586, mips32r2, mips64, ppc7400, or cortexa8hf-neon.

    release_version is a string representing the release number of the Yocto Project:

               4.2.1, 4.2.1+snapshot

For example, the following SDK installer is for a 64-bit development host system and a i586-tuned target architecture based off the SDK for core-image-sato and using the current DISTRO snapshot:

poky-glibc-x86_64-core-image-sato-i586-toolchain-DISTRO.sh

Note

As an alternative to downloading an SDK, you can build the SDK installer. For information on building the installer, see the “Building an SDK Installer” section.

The SDK and toolchains are self-contained and by default are installed into the poky_sdk folder in your home directory. You can choose to install the extensible SDK in any location when you run the installer. However, because files need to be written under that directory during the normal course of operation, the location you choose for installation must be writable for whichever users need to use the SDK.

The following command shows how to run the installer given a toolchain tarball for a 64-bit x86 development host system and a 64-bit x86 target architecture. The example assumes the SDK installer is located in ~/Downloads/ and has execution rights:

$ ./Downloads/poky-glibc-x86_64-core-image-sato-i586-toolchain-4.2.1.sh
Poky (Yocto Project Reference Distro) SDK installer version 4.2.1
===============================================================
Enter target directory for SDK (default: /opt/poky/4.2.1):
You are about to install the SDK to "/opt/poky/4.2.1". Proceed [Y/n]? Y
Extracting SDK........................................ ..............................done
Setting it up...done
SDK has been successfully set up and is ready to be used.
Each time you wish to use the SDK in a new shell session, you need to source the environment setup script e.g.
 $ . /opt/poky/4.2.1/environment-setup-i586-poky-linux

Note

If you do not have write permissions for the directory into which you are installing the SDK, the installer notifies you and exits. For that case, set up the proper permissions in the directory and run the installer again.

Again, reference the “Installed Standard SDK Directory Structure” section for more details on the resulting directory structure of the installed SDK.

3.3 Running the SDK Environment Setup Script

Once you have the SDK installed, you must run the SDK environment setup script before you can actually use the SDK. This setup script resides in the directory you chose when you installed the SDK, which is either the default /opt/poky/4.2.1 directory or the directory you chose during installation.

Before running the script, be sure it is the one that matches the architecture for which you are developing. Environment setup scripts begin with the string “environment-setup” and include as part of their name the tuned target architecture. As an example, the following commands set the working directory to where the SDK was installed and then source the environment setup script. In this example, the setup script is for an IA-based target machine using i586 tuning:

$ source /opt/poky/4.2.1/environment-setup-i586-poky-linux

When you run the setup script, the same environment variables are defined as are when you run the setup script for an extensible SDK. See the “Installed Extensible SDK Directory Structure” section for more information.