Getting Started with Yocto on i.MX Applications Processors

Introduction

This comprehensive guide walks you through setting up a Yocto build environment for NXP's i.MX applications processors. Whether you're developing an automotive infotainment system, industrial HMI, or IoT gateway, this guide provides the foundational knowledge needed to build custom Linux distributions for i.MX hardware.

Yocto Project is an open-source collaboration project that provides templates, tools, and methods to help you create custom Linux-based systems regardless of the hardware architecture. When combined with NXP's i.MX Board Support Packages (BSPs), it enables rapid development of production-ready embedded Linux solutions.

What You'll Learn

• Setting up a Yocto build environment
• Configuring for i.MX 8M hardware
• Building a minimal image
• Customizing your Linux distribution
• Deploying to i.MX hardware

Prerequisites

Before starting, ensure you have:

• Ubuntu 18.04 LTS or newer (recommended)
• At least 100GB of free disk space
• 8GB RAM (16GB recommended)
• Internet connection for downloading sources
• NXP i.MX development board (e.g., i.MX 8M Mini EVK)

Required Packages

Install the necessary packages on your Ubuntu system:

sudo apt-get install gawk wget git-core diffstat unzip texinfo gcc-multilib \
build-essential chrpath socat cpio python3 python3-pip python3-pexpect \
xz-utils debianutils iputils-ping python3-git python3-jinja2 libegl1-mesa \
libsdl1.2-dev pylint3 xterm sed cvs subversion mercurial
                        

Setting Up the Yocto Environment

Follow these steps to set up your Yocto environment for i.MX development:

Step 1: Clone the Yocto Project

Clone the latest Yocto Project release:

git clone https://git.yoctoproject.org/poky
cd poky
git checkout kirkstone
                        

Step 2: Clone NXP's BSP Layer

Download NXP's meta-fsl-bsp-release layer:

git clone https://github.com/Freescale/meta-freescale.git
cd meta-freescale
git checkout kirkstone
cd ..
                        

Step 3: Initialize the Build Environment

Initialize the build environment with:

source oe-init-build-env
                        

Configuration for i.MX 8M

Configure your build for the i.MX 8M hardware by modifying the build configuration files:

Machine Configuration

Edit conf/local.conf to set your machine:

MACHINE ??= "imx8mmevk"
# For other i.MX 8M variants:
# MACHINE ??= "imx8mnevk"    # i.MX 8M Nano
# MACHINE ??= "imx8mpevk"    # i.MX 8M Plus
                        

BBLayers Configuration

Edit conf/bblayers.conf to include the required layers:

POKY_BBLAYERS_CONF_VERSION = "2"

BBPATH = "${TOPDIR}"
BBFILES = ""

BBLAYERS ?= " \
  ${TOPDIR}/../meta \
  ${TOPDIR}/../meta-poky \
  ${TOPDIR}/../meta-yocto-bsp \
  ${TOPDIR}/../meta-freescale \
  ${TOPDIR}/../meta-freescale-3rdparty \
  ${TOPDIR}/../meta-freescale-demos \
  "
                        

Building Your First Image

With the environment configured, build your first image:

bitbake core-image-base
                        

This will take some time (2-4 hours depending on your system) as it downloads sources and builds the entire system from scratch.

Alternative Images

For different use cases, you can build alternative images:

• core-image-minimal - Minimal console-only image
• core-image-weston - Image with Weston Wayland compositor
• core-image-full-cmdline - Full command-line with more packages

Customization Examples

Yocto allows extensive customization. Here are some common customizations:

Adding Packages

To add packages to your image, create a custom image recipe in conf/local.conf:

IMAGE_INSTALL_append = " packagegroup-core-buildessential vim python3"
                        

Custom Kernel Configuration

For custom kernel configuration, create a machine-specific config file:

# Create a .scc file with your changes
# Add to your local.conf:
PREFERRED_PROVIDER_virtual/kernel = "linux-imx"
KERNEL_FEATURES_append = " features/debug/debug-enabled.scc"
                        

Deployment to Hardware

After building, deploy the image to your i.MX board:

SD Card Deployment

Flash the built image to an SD card:

sudo dd if=tmp/deploy/images/imx8mmevk/core-image-base-imx8mmevk.wic of=/dev/sdX bs=1M
sudo sync
                        

Network Deployment

For network deployment, use the TFTP method:

1. Start a TFTP server with the kernel and device tree
2. Configure your board to boot from network
3. Load the kernel via TFTP
4. Mount root filesystem via NFS

Troubleshooting

Common issues and solutions:

Build Failures

If builds fail due to missing dependencies:

• Check that all required packages are installed
• Verify the correct branch is checked out
• Check disk space availability

Hardware Boot Issues

If the board doesn't boot the deployed image:

• Verify proper SD card formatting
• Check U-Boot environment variables
• Ensure proper power supply to the board

Next Steps

Now that you've set up your Yocto environment for i.MX development, consider these next steps:

• Explore NXP's Yocto documentation for advanced configurations
• Try building for different i.MX processor variants
• Implement custom layers for your specific requirements
• Set up automated builds with CI/CD pipelines

Need further assistance? Contact our NXP-certified FAEs for personalized support.

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