Building an i.MX Development Environment (Yocto Edition) | Technical Column

Overall flow

Here is the overall flow for building an i.MX development environment using Yocto:

① Preparation: Setting up the host machine
② Let's build a development environment: Build a development environment with Yocto
③ Let's try building it: Build the image
④ Let's try writing: Write the generated image to the evaluation board

In this column, we will introduce steps 1 to 3 (" 3. Preparations", "4. Creating a development environment", and "5.  Building"), and step 4 will be introduced in the next column. Also, an image refers to a boot image that contains a Linux file system.

Overall flow for building an i.MX development environment using Yocto

Know the hardware you need

Building images for the i.MX evaluation board using the Yocto Project build environment is covered in the NXP i.MX Yocto Project User's Guide.

The following i.MX products support the Yocto Project build environment:

In this column, we will introduce how to set up the environment using the evaluation board "i.MX 8M Plus" equipped with i.MX 8M Plus.

Reference image: i.MX 8M Plus

• Reference URL: 8MPLUSLPD4-EVK
• Reference URL: i.MX Yocto Project User's Guide
• Reference URL: Embedded Linux for i.MX Applications Processors

Set up the host machine. The host machine requirements are as follows:

If the above requirements are met, there will be no problem as a host machine. However, we recommend a HDD capacity of 500GB or more. The recommended HDD capacity is 250GB, but when you build, including intermediate files and generated files, a considerable amount of HDD capacity will be used. Considering future expandability, it is safer to have an HDD capacity of 500GB or more.

In addition, an Internet connection is required to run the Yocto environment. If you are using it in a company environment, you may need to configure a proxy or other settings to connect to the Internet from behind a firewall. Please consult with your company's IT department.

The host machine used in this column was the PC that the author uses for development work. Therefore, various packages used in building the Yocto environment were pre-installed. If your host machine is missing any packages, please install the software or packages according to the error message.

1. Update package information required for Yocto

Command operations are performed in the host machine's terminal. No directory is specified.

The command content is shown below.

When the prompt symbol ($) appears in the terminal, proceed to the next step.

2. Install the packages required for Yocto

Install the packages required to build the Yocto Project.

The command content is shown below.

When the prompt symbol ($) appears in the terminal, proceed to the next step.

3. Set up the swap file

When building on the host machine, builds are performed for each thread. If the memory size used by the thread exceeds the memory size of the host machine, a build error will occur. To avoid this, set up a swap file (32GB).

Note: If the host machine has sufficient memory, this step is not necessary.

The command content is shown below.

When the prompt symbol ($) appears in the terminal, proceed to the next step.

Build the Yocto i.MX development environment on the host machine.

1. Install the repo utility

The command content is shown below.

When the prompt symbol ($) appears in the terminal, proceed to the next step.

2. Install git

The command content is shown below.

When the prompt symbol ($) appears in the terminal, proceed to the next step.

3. Set up Yocto

Set up Yocto. Create the directory imx-yocto-bsp and set up Yocto in it. Select and download the manifest file you want to use from https://github.com/nxp-imx/imx-manifest/tree/imx-linux-scarthgap. In this article, we will use imx-6.6.36-2.1.0.xml.

• https://github.com/nxp-imx/imx-manifest/tree/imx-linux-scarthgap

The command content is shown below.

When the prompt symbol ($) appears in the terminal, proceed to the next step.

4. Select the build target and supported window systems (graphics capabilities)

i.MX provides a script file (imx-setup-release.sh) that simplifies the setup of the build image. To use this script file, execute the script by specifying the name of the evaluation board and distribution to be built.

The names of evaluation boards that can be specified in the script file are listed below.

The names of distributions that can be specified in the script file are listed below.

In this column, we will use the imx8mp-lpddr4-evk, which is compatible with i.MX8M Plus, and the fsl-imx-xwayland, which includes graphics functions (Wayland, X11).

Run the script file with the following command:

Let's try building (bitbake) in the development environment created in the previous section.

1. Select the i.MX image

Yocto Project provides several images. You can select one of them to build the features you need and generate an image.

The image names are listed below.

You can use any of the images listed above, but in this article we will use imx-image-full.

2. Run the build (bitbake)

In Yocto, the build is performed using the bitbake command.

• *The build process may take several tens of hours.

If the message "all succeeded" is returned on the console screen, the build is successful.

• Supplementary information

Depending on the performance of the host machine, a build may take several hours to several tens of hours. By default, the bitbake command generates the same number of threads as the number of multi-cores on the host machine to speed up the build process. Therefore, if memory capacity is insufficient when memory is allocated for each thread, swapping may occur or the build may stop due to a build error depending on the order of build generation. In that case, we recommend that you run bitbake again in section 4.4 or limit parallel processing during the build.

Below is an example of the execution command when the number of threads is 2.

About the next column

In the next article, we will try to write the image file created in this column to an i.MX evaluation board.

Conclusion

This time, we explained how to build a Yocto development environment for the i.MX series. By actually building a development environment, you will gain a deeper understanding of the i.MX series and be able to see the finer details of the construction method. In the next column, we will write the image file generated this time to an evaluation board. In addition, the NEXTY Electronics Development Department is engaged in product development and technical support using the i.MX series, so please feel free to contact us.