# Working Within Eclipse

The Eclipse IDE is a popular development environment and it fully supports development using Yocto Project. When you install and configure the Eclipse Yocto Project Plug-in into the Eclipse IDE you maximize your Yocto Project design experience. Installing and configuring the Plug-in results in an environment that has extensions specifically designed to let you more easily develop software. These extensions allow for cross-compilation and deployment and execution of your output into a QEMU emulation session. You can also perform cross-debugging and profiling. The environment also has a suite of tools that allows you to perform remote profiling, tracing, collection of power data, collection of latency data, and collection of performance data.

This section describes how to install and configure the Eclipse IDE Yocto Plug-in and how to use it to develop your Yocto Project.

## Setting Up the Eclipse IDE

To develop within the Eclipse IDE you need to do the following:

1. Be sure the optimal version of Eclipse IDE is installed.

2. Install required Eclipse plug-ins prior to installing the Eclipse Yocto Plug-in.

3. Configure the Eclipse Yocto Plug-in.

### Installing Eclipse IDE

It is recommended that you have the Helios 3.6.1 version of the Eclipse IDE installed on your development system. If you don’t have this version you can find it at . From that site, choose the Eclipse Classic version. This version contains the Eclipse Platform, the Java Development Tools (JDT), and the Plug-in Development Environment.

Once you have downloaded the tarball, extract it into a clean directory and complete the installation.

One issue exists that you need to be aware of regarding the Java Virtual machine’s garbage collection (GC) process. The GC process does not clean up the permanent generation space (PermGen). This space stores meta-data descriptions of classes. The default value is set too small and it could trigger an out-of-memory error such as the following:

         Java.lang.OutOfMemoryError: PermGen space

This error causes the application to hang.

To fix this issue you can use the &dash;&dash;vmargs option when you start Eclipse to increase the size of the permanent generation space:

         eclipse &dash;&dash;vmargs &dash;&dash;XX:PermSize=256M

### Installing Required Plug-ins and the Eclipse Yocto Plug-in

Before installing the Yocto Plug-in you need to be sure that the CDT 7.0, RSE 3.2, and Autotools plug-ins are all installed in the following order. After installing these three plug-ins, you can install the Eclipse Yocto Plug-in. Use the following URLs for the plug-ins:

1. CDT 7.0 – : For CDT main features select the checkbox so you get all items. For CDT optional features expand the selections and check “C/C++ Remote Launch”.

2. RSE 3.2 – : Check the box next to “TM and RSE Main Features” so you select all those items. Note that all items in the main features depend on 3.2.1 version. Expand the items under “TM and RSE Uncategorized 3.2.1” and select the following: “Remote System Explorer End-User Runtime”, “Remote System Explorer Extended SDK”, “Remote System Explorer User Actions”, “RSE Core”, “RSE Terminals UI”, and “Target Management Terminal”.

3. Autotools – : Expand the items under “Linux Tools” and select “Autotools support for CDT (Incubation)”.

4. Yocto Plug-in – : Check the box next to “Development tools & SDKs for Yocto Linux” to select all the items.

Follow these general steps to install a plug-in:

1. From within the Eclipse IDE select the “Install New Software” item from the “Help” menu.

2. Click “Add…” in the “Work with:” area.

3. Enter the URL for the repository and leave the “Name” field blank.

4. Check the boxes next to the software you need to install and then complete the installation. For information on the specific software packages you need to include, see the previous list.

### Configuring the Plug-in

Configuring the Eclipse Yocto Plug-in involves choosing the Cross Compiler Options, selecting the Target Architecture, and choosing the Target Options. These settings are the default settings for all projects. You do have opportunities to change them later if you choose to when you configure the project. See “Configuring the Cross Toolchain” section later in the manual.

To start, you need to do the following from within the Eclipse IDE:

- Choose Windows -> Preferences to display the Preferences Dialog

- Click “Yocto SDK”

#### Configuring the Cross-Compiler Options

Choose between ‘SDK Root Mode’ and ‘Poky Tree Mode’ for Cross Compiler Options.

- SDK Root Mode – Select this mode when you are not concerned with building an image or you do not have a Poky build tree on your system. For example, suppose you are an application developer and do not need to build an image. You just want to use an architecture-specific toolchain on an existing kernel and root filesystem. When you use SDK Root Mode you are using the toolchain installed in the `/opt/poky` directory.

- Poky Tree Mode – Select this mode if you are concerned with building images for hardware or your development environment already has a build tree. In this case you likely already have a Poky build tree installed on your system or you (or someone else) will be building one. When you use the Poky Tree Mode you are using the toolchain bundled inside the Poky build tree. If you use this mode you must also supply the Poky Root Location in the Preferences Dialog.

#### Configuring the Sysroot

Specify the sysroot, which is used by both the QEMU user-space NFS boot process and by the cross-toolchain regardless of the mode you select (SDK Root Mode or Poky Tree Mode). For example, sysroot is the location to which you extract the downloaded image’s root filesystem to through the ADT Installer.

#### Selecting the Target Architecture

Use the pull-down Target Architecture menu and select the target architecture.

The Target Architecture is the type of hardware you are going to use or emulate. This pull-down menu should have the supported architectures. If the architecture you need is not listed in the menu then you will need to re-visit “Preparing to Use the Application Development Toolkit (ADT)” section earlier in this document.

#### Choosing the Target Options

You can choose to emulate hardware using the QEMU emulator, or you can choose to use actual hardware.

- External HW – Select this option if you will be using actual hardware.

- QEMU – Select this option if you will be using the QEMU emulator. If you are using the emulator you also need to locate the Kernel and you can specify custom options.

  In Poky Tree Mode the kernel you built will be located in the Poky Build tree in `tmp/deploy/images` directory. In SDK Root Mode the pre-built kernel you downloaded is located in the directory you specified when you downloaded the image.

  Most custom options are for advanced QEMU users to further customize their QEMU instance. These options are specified between paired angled brackets. Some options must be specified outside the brackets. In particular, the options `serial`, `nographic`, and `kvm` must all be outside the brackets. Use the `man qemu` command to get help on all the options and their use. The following is an example:

          serial ‘<-m 256 -full-screen>’

  Regardless of the mode, Sysroot is already defined in the “Sysroot” field.

Click the “OK” button to save your plug-in configurations.

## Creating the Project

You can create two types of projects: Autotools-based, or Makefile-based. This section describes how to create autotools-based projects from within the Eclipse IDE. For information on creating projects in a terminal window see “Using the Command Line” section.

To create a project based on a Yocto template and then display the source code, follow these steps:

1. Select File -> New -> Project.

2. Double click “CC++”.

3. Double click “C Project” to create the project.

4. Double click “Yocto SDK Project”.

5. Select “Hello World ANSI C Autotools Project”. This is an Autotools-based project based on a Yocto Project template.

6. Put a name in the “Project name:” field.

7. Click “Next”.

8. Add information in the “Author” field.

9. Use “GNU General Public License v2.0” for the License.

10. Click “Finish”.

11. Answer ‘Yes” to the open perspective prompt.

12. In the Project Explorer expand your project.

13. Expand ‘src’.

14. Double click on your source file and the code appears in the window. This is the template.

## Configuring the Cross-Toolchains

The previous section, “Configuring the Cross-Compiler Options”, set up the default project configurations. You can change these settings for a given project by following these steps:

1. Select Project -> Invoke Yocto Tools -> Reconfigure Yocto. This brings up the project Yocto Settings Dialog. Settings are inherited from the default project configuration. The information in this dialogue is identical to that chosen earlier for the Cross Compiler Option (SDK Root Mode or Poky Tree Mode), the Target Architecture, and the Target Options. The settings are inherited from the Yocto Plug-in configuration performed after installing the plug-in.

2. Select Project -> Reconfigure Project. This runs the `autogen.sh` in the workspace for your project. The script runs `libtoolize`, `aclocal`, `autoconf`, `autoheader`, `automake &dash;&dash;a`, and `./configure`.

## Building the Project

To build the project, select Project -> Build Project. You should see the console updated and you can note the cross-compiler you are using.

## Starting QEMU in User Space NFS Mode

To start the QEMU emulator from within Eclipse, follow these steps:

1. Select Run -> External Tools -> External Tools Configurations... This selection brings up the External Tools Configurations Dialogue.

2. Go to the left navigation area and expand ‘Program’. You should find the image listed. For example, qemu-x86_64-poky-linux.

3. Click on the image. This brings up a new environment in the main area of the External Tools Configurations Dialogue. The Main tab is selected.

4. Click “Run” next. This brings up a shell window.

5. Enter your host root password in the shell window at the prompt. This sets up a Tap 0 connection needed for running in user-space NFS mode.

6. Wait for QEMU to launch.

7. Once QEMU launches you need to determine the IP Address for the user-space NFS. You can do that by going to a terminal in the QEMU and entering the `ipconfig` command.

## Deploying and Debugging the Application

Once QEMU is running you can deploy your application and use the emulator to perform debugging. Follow these steps to deploy the application.

1. Select Run -> Debug Configurations...

2. In the left area expand “C/C++Remote Application”.

3. Locate your project and select it to bring up a new tabbed view in the Debug Configurations dialogue.

4. Enter the absolute path into which you want to deploy the application. Use the Remote Absolute File Path for C/C++Application:. For example, enter `/usr/bin/<programname>`.

5. Click on the Debugger tab to see the cross-tool debugger you are using.

6. Create a new connection to the QEMU instance by clicking on “new”.

7. Select “TCF, which means Target Communication Framework.

8. Click “Next”.

9. Clear out the “host name” field and enter the IP Address determined earlier.

10. Click Finish to close the new connections dialogue.

11. Use the drop-down menu now in the “Connection” field and pick the IP Address you entered.

12. Click “Debug” to bring up a login screen and login.

13. Accept the debug perspective.

## Running User-Space Tools

As mentioned earlier in the manual several tools exist that enhance your development experience. These tools are aids in developing and debugging applications and images. You can run these user-space tools from within the Yocto Eclipse Plug-in through the Window -> YoctoTools menu.

Once you pick a tool you need to configure it for the remote target. Every tool needs to have the connection configured. You must select an existing TCF-based RSE connection to the remote target. If one does not exist, click "New" to create one.

Here are some specifics about the remote tools:

- OProfile: Selecting this tool causes the oprofile-server on the remote target to launch on the local host machine. The oprofile-viewer must be installed on the local host machine and the oprofile-server must be installed on the remote target, respectively, in order to use. You can locate both the viewer and server from . You need to compile and install the oprofile-viewer from the source code on your local host machine. The oprofile-server is installed by default in the image.

- Lttng-ust: Selecting this tool runs "usttrace" on the remote target, transfers the output data back to the local host machine and uses "lttv-gui" to graphically display the output. The "lttv-gui" must be installed on the local host machine to use this tool. For information on how to use "lttng" to trace an application, see .

  For "Application" you must supply the absolute path name of the application to be traced by user mode lttng. For example, typing `/path/to/foo` triggers `usttrace /path/to/foo` on the remote target to trace the program `/path/to/foo`.

  "Argument" is passed to `usttrace` running on the remote target.

- PowerTOP: Selecting this tool runs "PowerTOP" on the remote target machine and displays the results in a new view called "powertop".

  "Time to gather data(sec):" is the time passed in seconds before data is gathered from the remote target for analysis.

  "show pids in wakeups list:" corresponds to the -p argument passed to "powertop".

- LatencyTOP and Perf: "LatencyTOP" identifies system latency, while "perf" monitors the system's performance counter registers. Selecting either of these tools causes an RSE terminal view to appear from which you can run the tools. Both tools refresh the entire screen to display results while they run.