Install the Kernel Locally

Introduction

Make sure you have set up your development environment before following these steps. This page will guide you through the process of installing the kernel locally on your machine. It will be installed in addition to your distro’s default kernel so that you can always change back to that in case something goes wrong. If you are interested in learning more about this process, there are lots of online guides available, for example Fedora* Quick Docs or this wiki page.

Build and install the kernel

  1. Change directory to ~/sof/linux that you created on the setup page.

  2. Load the base kernel configuration.

    The following command copies the configuration of the booted kernel so that it will be used as a base:

    cp /boot/config-$(uname -r)* .config
    
  3. Apply the SOF-specific configuration.

    The following scripts update your base configuration so that it uses the latest SOF modules. Run only one of them depending on your needs. If it prompts you with any questions, just press Enter to accept the default value. Note that, by default, these scripts will set the configuration to only compile modules that are currently loaded in order to lower compile times. This means that when you’ve booted from the custom kernel, some external devices may not work if they were not connected while running this script. If you want to compile all modules, delete the line make localmodconfig from the script you will run in this step.

    • For most users:

      ../kconfig/kconfig-distro-sof-update.sh
      
    • For additional logging and experimental device support:

      ../kconfig/kconfig-distro-sof-dev-update.sh
      
  4. Compile the kernel.

    The first time you run this command, it can take a while (over 30 minutes on some machines), so grab a coffee or take an exercise break while it runs.

    make -j$(nproc --all)
    
  5. Install the kernel.

    sudo make modules_install
    sudo make install
    

If all went well, your freshly-built kernel will be installed and available at next boot. Restart your computer, and you should have the option to pick a kernel when it turns on. Select the kernel which name has -sof at the end of it, and your computer should boot as normal using the kernel you just built. On Ubuntu*, the kernel option may be hidden behind the Advanced options for Ubuntu submenu.

Update and rebuild

If you need to try some new changes, download the updated code and rebuild the kernel.

Update the kernel cloned with git

If you originally cloned the repo using git, perform the following steps to update and rebuild the kernel:

  1. Pull the changes.

    git pull
    
  2. Clean the directory.

    Note

    You should clean up after switching branches or configuration or any other major code change. If you just pulled some minor updates, it’s likely unnecessary and will increase your build time.

    make clean
    
  3. Repeat steps 4 and 5 to rebuild and reinstall the kernel.

  4. Reboot your computer, and select the kernel with -sof at the end of its name to test it.

Update the kernel downloaded via zip

Unfortunately, if you downloaded via zip, the entire process has to be restarted from the Get the kernel source step. There is no good way to incrementally update. However, the kernel build should be faster now as part of it will be cached.

Make sure you delete the old folder before starting over:

cd ..
rm -rf linux

Remove the kernel

If you run into issues or no longer need the custom kernel, you can remove it.

  • Ubuntu:

    cd ~/sof/linux
    sudo rm /boot/*-$(make kernelversion)
    sudo rm -rf /lib/modules/$(make kernelversion)
    sudo update-grub
    
  • Fedora:

    cd ~/sof/linux
    sudo rm /boot/*-$(make kernelversion)*
    sudo rm -rf /lib/modules/$(make kernelversion)
    sudo grubby --remove-kernel=/boot/vmlinuz-$(make kernelversion)
    

After rebooting, you should be back to your old kernel with all traces of the custom kernel installation gone. If you’d like, you can also delete the ~sof directory to save disk space.