%poky; ] > In order to develop applications, you need set up your host development system. Several ways exist that allow you to install cross-development tools, QEMU, the Eclipse Yocto Plug-in, and other tools. This chapter describes how to prepare for application development.

The following list describes installation methods that set up varying degrees of tool availabiltiy on your system. Regardless of the installation method you choose, you must source the cross-toolchain environment setup script before you use a toolchain. See the "Setting Up the Cross-Development Environment" section for more information. Avoid mixing installation methods when installing toolchains for different architectures. For example, avoid using the ADT Installer to install some toolchains and then hand-installing cross-development toolchains by running the toolchain installer for different architectures. Mixing installation methods can result in situations where the ADT Installer becomes unreliable and might not install the toolchain. If you must mix installation methods, you might avoid problems by deleting /var/lib/opkg, thus purging the opkg package metadata Use the ADT Installer Script: This method is the recommended way to install the ADT because it automates much of the process for you. For example, you can configure the installation to install the QEMU emulator and the user-space NFS, specify which root filesystem profiles to download, and define the target sysroot location. Use an Existing Toolchain: Using this method, you select and download an architecture-specific toolchain installer and then run the script to hand-install the toolchain. If you use this method, you just get the cross-toolchain and QEMU - you do not get any of the other mentioned benefits had you run the ADT Installer script. Use the Toolchain from within the Build Directory: If you already have a Build Directory, you can build the cross-toolchain within the directory. However, like the previous method mentioned, you only get the cross-toolchain and QEMU - you do not get any of the other benefits without taking separate steps.

To run the ADT Installer, you need to get the ADT Installer tarball, be sure you have the necessary host development packages that support the ADT Installer, and then run the ADT Installer Script. For a list of the host packages needed to support ADT installation and use, see the "ADT Installer Extras" lists in the "Required Packages for the Host Development System" section of the Yocto Project Reference Manual.

The ADT Installer is contained in the ADT Installer tarball. You can download the tarball into any directory from the Index of Releases, specifically at . Or, you can use BitBake to generate the tarball inside the existing Build Directory. If you use BitBake to generate the ADT Installer tarball, you must source the environment setup script (&OE_INIT_FILE;) located in the Source Directory before running the bitbake command that creates the tarball. The following example commands download the Poky tarball, set up the Source Directory, set up the environment while also creating the default Build Directory, and run the bitbake command that results in the tarball ~/yocto-project/build/tmp/deploy/sdk/adt_installer.tar.bz2: $ cd ~ $ mkdir yocto-project $ cd yocto-project $ wget &YOCTO_RELEASE_DL_URL;/&YOCTO_POKY_TARBALL; $ tar xjf &YOCTO_POKY_TARBALL; $ source &OE_INIT_PATH; $ bitbake adt-installer

Before running the ADT Installer script, you need to unpack the tarball. You can unpack the tarball in any directory you wish. For example, this command copies the ADT Installer tarball from where it was built into the home directory and then unpacks the tarball into a top-level directory named adt-installer: $ cd ~ $ cp ~/poky/build/tmp/deploy/sdk/adt_installer.tar.bz2 $HOME $ tar -xjf adt_installer.tar.bz2 Unpacking the tarball creates the directory adt-installer, which contains the ADT Installer script (adt_installer), its configuration file (adt_installer.conf), a scripts directory, and an opkg directory. Before you run the ADT Installer script, however, you should examine the ADT Installer configuration file and be sure you are going to get what you want. Your configurations determine which kernel and filesystem image are downloaded. The following list describes the configurations you can define for the ADT Installer. For configuration values and restrictions, see the comments in the adt-installer.conf file: YOCTOADT_REPO: This area includes the IPKG-based packages and the root filesystem upon which the installation is based. If you want to set up your own IPKG repository pointed to by YOCTOADT_REPO, you need to be sure that the directory structure follows the same layout as the reference directory set up at . Also, your repository needs to be accessible through HTTP. Additionally, you will need to edit a second configuration file located in the adt-installer/opkg directory. The configuration file you edit depends on your host development system. For 64-bit systems, edit the opkg-sdk-x86_64.conf file. If your host development system is 32-bit, edit the opkg-sdk-i686.conf file. For both cases, you need to make sure you are pointing to the IPKG-based packages specified by the YOCTOADT_REPO. Here is an example for a 64-bit development system: src yp-x86_64-nativesdk http://my_repo/yp-1.3.1/adt-ipk/x86_64-nativesdk YOCTOADT_TARGETS: The machine target architectures for which you want to set up cross-development environments. YOCTOADT_QEMU: Indicates whether or not to install the emulator QEMU. YOCTOADT_NFS_UTIL: Indicates whether or not to install user-mode NFS. If you plan to use the Eclipse IDE Yocto plug-in against QEMU, you should install NFS. To boot QEMU images using our userspace NFS server, you need to be running portmap or rpcbind. If you are running rpcbind, you will also need to add the -i option when rpcbind starts up. Please make sure you understand the security implications of doing this. You might also have to modify your firewall settings to allow NFS booting to work. YOCTOADT_ROOTFS_<arch>: The root filesystem images you want to download from the YOCTOADT_IPKG_REPO repository. YOCTOADT_TARGET_SYSROOT_IMAGE_<arch>: The particular root filesystem used to extract and create the target sysroot. The value of this variable must have been specified with YOCTOADT_ROOTFS_<arch>. For example, if you downloaded both minimal and sato-sdk images by setting YOCTOADT_ROOTFS_<arch> to "minimal sato-sdk", then YOCTOADT_ROOTFS_<arch> must be set to either minimal or sato-sdk. YOCTOADT_TARGET_SYSROOT_LOC_<arch>: The location on the development host where the target sysroot is created. After you have configured the adt_installer.conf file, run the installer using the following command. Be sure that you are not trying to use cross-compilation tools. When you run the installer, the environment must use a host gcc: $ cd ~/adt-installer $ ./adt_installer Once the installer begins to run, you are asked to enter the location for cross-toolchain installation. The default location is /opt/poky/<release>. After selecting the location, you are prompted to run in interactive or silent mode. If you want to closely monitor the installation, choose “I” for interactive mode rather than “S” for silent mode. Follow the prompts from the script to complete the installation. Once the installation completes, the ADT, which includes the cross-toolchain, is installed. You will notice environment setup files for the cross-toolchain in &YOCTO_ADTPATH_DIR;, and image tarballs in the adt-installer directory according to your installer configurations, and the target sysroot located according to the YOCTOADT_TARGET_SYSROOT_LOC_<arch> variable also in your configuration file.

If you want to simply install the cross-toolchain by hand, you can do so by running the toolchain installer. If you use this method to install the cross-toolchain and you still need to install the target sysroot, you will have to extract and install sysroot separately. For information on how to do this, see the "Extracting the Root Filesystem" section. Follow these steps: Go to and find the folder that matches your host development system (i.e. i686 for 32-bit machines or x86-64 for 64-bit machines). Go into that folder and download the toolchain installer whose name includes the appropriate target architecture. For example, if your host development system is an Intel-based 64-bit system and you are going to use your cross-toolchain for an Intel-based 32-bit target, go into the x86_64 folder and download the following installer: poky-eglibc-x86_64-i586-toolchain-gmae-&DISTRO;.sh As an alternative to steps one and two, you can build the toolchain installer if you have a Build Directory. If you need GMAE, you should use the bitbake meta-toolchain-gmae command. The resulting installation script when run will support such development. However, if you are not concerned with GMAE, you can generate the toolchain installer using bitbake meta-toolchain. Use the appropriate bitbake command only after you have sourced the &OE_INIT_PATH; script located in the Source Directory. When the bitbake command completes, the toolchain installer will be in tmp/deploy/sdk in the Build Directory. Once you have the installer, run it to install the toolchain. You must change the permissions on the toolchain installer script so that it is executable. The following command shows how to run the installer given a toolchain tarball for a 64-bit development host system and a 32-bit target architecture. The example assumes the toolchain installer is located in ~/Downloads/. $ ~/Downloads/poky-eglibc-x86_64-i586-toolchain-gmae-&DISTRO;.sh If you do not have write permissions for the directory into which you are installing the toolchain, the toolchain installer notifies you and exits. Be sure you have write permissions in the directory and run the installer again. Once the tarball is expanded, the cross-toolchain is installed. You will notice environment setup files for the cross-toolchain in the directory.

A final way of making the cross-toolchain available is to use BitBake to generate the toolchain within an existing Build Directory. This method does not install the toolchain into the /opt directory. As with the previous method, if you need to install the target sysroot, you must do that separately as well. Follow these steps to generate the toolchain into the Build Directory: Source the environment setup script &OE_INIT_FILE; located in the Source Directory. At this point, you should be sure that the MACHINE variable in the local.conf file found in the conf directory of the Build Directory is set for the target architecture. Comments within the local.conf file list the values you can use for the MACHINE variable. You can populate the Build Directory with the cross-toolchains for more than a single architecture. You just need to edit the MACHINE variable in the local.conf file and re-run the BitBake command. Run bitbake meta-ide-support to complete the cross-toolchain generation. If you change out of your working directory after you source the environment setup script and before you run the bitbake command, the command might not work. Be sure to run the bitbake command immediately after checking or editing the local.conf but without changing out of your working directory. Once the bitbake command finishes, the cross-toolchain is generated and populated within the Build Directory. You will notice environment setup files for the cross-toolchain in the Build Directory in the tmp directory. Setup script filenames contain the strings environment-setup. Be aware that when you use this method to install the toolchain you still need to separately extract and install the sysroot filesystem. For information on how to do this, see the "Extracting the Root Filesystem" section.

Before you can develop using the cross-toolchain, you need to set up the cross-development environment by sourcing the toolchain's environment setup script. If you used the ADT Installer or hand-installed cross-toolchain, then you can find this script in the &YOCTO_ADTPATH_DIR; directory. If you installed the toolchain in the Build Directory, you can find the environment setup script for the toolchain in the Build Directory's tmp directory. Be sure to run the environment setup script 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 architecture. For example, the toolchain environment setup script for a 64-bit IA-based architecture would be the following: &YOCTO_ADTPATH_DIR;/environment-setup-x86_64-poky-linux

You will need to have a kernel and filesystem image to boot using your hardware or the QEMU emulator. Furthermore, if you plan on booting your image using NFS or you want to use the root filesystem as the target sysroot, you need to extract the root filesystem.

To get the kernel and filesystem images, you either have to build them or download pre-built versions. You can find examples for both these situations in the "A Quick Test Run" section of the Yocto Project Quick Start. The Yocto Project ships basic kernel and filesystem images for several architectures (x86, x86-64, mips, powerpc, and arm) that you can use unaltered in the QEMU emulator. These kernel images reside in the release area - and are ideal for experimentation using Yocto Project. For information on the image types you can build using the OpenEmbedded build system, see the "Images" chapter in the Yocto Project Reference Manual. If you are planning on developing against your image and you are not building or using one of the Yocto Project development images (e.g. core-image-*-dev), you must be sure to include the development packages as part of your image recipe. Furthermore, if you plan on remotely deploying and debugging your application from within the Eclipse IDE, you must have an image that contains the Yocto Target Communication Framework (TCF) agent (tcf-agent). By default, the Yocto Project provides only one type pre-built image that contains the tcf-agent. And, those images are SDK (e.g.core-image-sato-sdk). If you want to use a different image type that contains the tcf-agent, you can do so one of two ways: Modify the conf/local.conf configuration in the Build Directory and then rebuild the image. With this method, you need to modify the EXTRA_IMAGE_FEATURES variable to have the value of "tools-debug" before rebuilding the image. Once the image is rebuilt, the tcf-agent will be included in the image and is launched automatically after the boot. Manually build the tcf-agent. To build the agent, follow these steps: Be sure the ADT is installed as described in the "Installing the ADT and Toolchains" section. Set up the cross-development environment as described in the "Setting Up the Cross-Development Environment" section. Get the tcf-agent source code using the following commands: $ git clone http://git.eclipse.org/gitroot/tcf/org.eclipse.tcf.agent.git $ cd agent Modify the Makefile.inc file for the cross-compilation environment by setting the OPSYS and MACHINE variables according to your target. Use the cross-development tools to build the tcf-agent. Before you "Make" the file, be sure your cross-tools are set up first. See the "Makefile-Based Projects" section for information on how to make sure the cross-tools are set up correctly. If the build is successful, the tcf-agent output will be obj/$(OPSYS)/$(MACHINE)/Debug/agent. Deploy the agent into the image's root filesystem.

You must extract the root filesystem if you want to boot the image using NFS or you want to use the root filesystem as the target sysroot. For example, the Eclipse IDE environment with the Eclipse Yocto Plug-in installed allows you to use QEMU to boot under NFS. Another example is if you want to develop your target application using the root filesystem as the target sysroot. To extract the root filesystem, first source the cross-development environment setup script and then use the runqemu-extract-sdk command on the filesystem image. For example, the following commands set up the environment and then extract the root filesystem from a previously built filesystem image tarball named core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2. The example extracts the root filesystem into the $HOME/qemux86-sato directory: $ source $HOME/poky/build/tmp/environment-setup-i586-poky-linux $ runqemu-extract-sdk \ tmp/deploy/images/core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2 \ $HOME/qemux86-sato In this case, you could now point to the target sysroot at $HOME/qemux86-sato.