Sample_fs Usage When Building Your Own Kernel on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users are experiencing difficulties when attempting to build a custom kernel for the Nvidia Jetson Orin Nano Dev board, particularly related to the configuration and usage of the file system (rootfs). The primary symptoms include:

• Inability to access a graphical user interface (GUI) after booting, resulting in a black screen post-Nvidia splash screen, with only SSH access available.
• Confusion regarding the correct procedure for updating the rootfs to enable GUI support and OEM configuration.
• Uncertainty about whether the default rootfs provided is suitable for their needs or if they should create a custom one.

The issue typically arises during the setup phase when users try to modify the rootfs to include GUI support. Users have reported varying success rates, with some successfully booting into a desktop environment using DisplayPort (DP) and HDMI, while others face persistent display issues. The problem impacts user experience significantly, as it prevents access to the expected graphical interface and limits functionality.

Possible Causes

Several potential causes for these issues have been identified:

• Hardware Incompatibilities: The Orin Nano only supports HDMI output when used with specific carrier boards; using incompatible hardware may result in display issues.

• Software Bugs or Conflicts: Issues may arise from bugs in the JetPack version or conflicts between installed packages and dependencies.

• Configuration Errors: Incorrect commands or configurations during the rootfs update process can lead to an incomplete or misconfigured system.

• Driver Issues: Missing or improperly configured display drivers may prevent video output.

• Environmental Factors: Power supply inconsistencies or overheating could affect system performance.

• User Errors: Misunderstandings regarding the installation process or incorrect command usage can lead to failures in achieving desired outcomes.

Troubleshooting Steps, Solutions & Fixes

To address the issues encountered when building a custom kernel and configuring the rootfs, follow these comprehensive troubleshooting steps:

1. Verify Hardware Compatibility:

   • Ensure that you are using the correct Nvidia DevKit (Orin Nano vs. Xavier NX).
   • Confirm that your monitor supports HDMI output if you are experiencing display issues.

2. Build Sample File System with GUI Support:

   • Use the following command to build a sample file system that includes GUI support:

     sudo ./nv_build_samplefs.sh --abi aarch64 --distro ubuntu --flavor desktop --version focal
     

   • This command generates a sample_fs.tbz2 file that contains necessary packages for GUI functionality.

3. Update Root Filesystem:

   • Untar the generated sample file system into your existing rootfs directory:

     sudo tar xpf tools/samplefs/sample_fs.tbz2 -C rootfs/
     

4. Check Display Output:

   • After flashing, check if both HDMI and DP outputs are functioning correctly. If HDMI works but DP does not, it may be due to hardware limitations of the Orin series.

5. Kernel Compilation Steps:

   • Follow these commands for compiling your kernel:

     export JETPACK=$HOME/nvidia/nvidia_sdk/JetPack_5.1.1_Linux_JETSON_ORIN_NANO_TARGETS/Linux_for_Tegra
     export KERNEL_OUT=$JETPACK/images
     
     cd ~/nvidia/nvidia_sdk/JetPack_5.1.1_Linux_JETSON_ORIN_NANO_TARGETS/Linux_for_Tegra/sources/kernel/kernel-5.10
     make ARCH=arm64 O=$KERNEL_OUT CROSS_COMPILE=$CROSS_COMPILE -j8 mrproper
     make ARCH=arm64 O=$KERNEL_OUT CROSS_COMPILE=$CROSS_COMPILE -j8 tegra_defconfig	
     make ARCH=arm64 O=$KERNEL_OUT CROSS_COMPILE=$CROSS_COMPILE -j8 Image
     make ARCH=arm64 O=$KERNEL_OUT CROSS_COMPILE=$CROSS_COMPILE -j8 dtbs
     make ARCH=arm64 O=$KERNEL_OUT CROSS_COMPILE=$CROSS_COMPILE -j8 modules
     make ARCH=arm64 O=$KERNEL_OUT INSTALL_MOD_PATH=$KERNEL_MODULES_OUT -j8 modules_install
     

6. Final Flashing Process:

   • Execute the following command to flash your device:

     sudo ./tools/kernel_flash/l4t_initrd_flash.sh --external-device mmcblk1p1 -c tools/kernel_flash/flash_l4t_external.xml --showlogs --network usb0 p3509-a02+p3767-0000 internal
     

7. Post-Boot Configuration:

   • After rebooting, if you still face issues with video output, check logs using:

     dmesg | less
     cat /var/log/Xorg.0.log | less
     

   • Look for errors related to display drivers or configuration issues.

8. Common Fixes:

   • If there’s no video output after following these steps, consider running:

     sudo depmod -a
     sudo reboot
     

   • If problems persist, revert to using the default BSP and sample rootfs provided by Nvidia for initial testing.

9. Documentation and Resources:

   • Refer to Nvidia’s official documentation for additional guidance on kernel customization and troubleshooting: Nvidia Developer Guide.

10. Best Practices:

    • Always ensure that you have backups of your configurations before making changes.
    • Regularly check for updates from Nvidia regarding JetPack releases and kernel support.

By following these steps, users should be able to resolve common issues related to building a custom kernel and configuring their file systems on the Nvidia Jetson Orin Nano Dev board effectively.