Proper way for building kernel in jetpack6 and jetson linux 36.3 for gadgetfs

Issue Overview

Users are experiencing difficulties when attempting to build a custom kernel for the Nvidia Jetson Orin Nano Dev board with GadgetFS enabled in Menuconfig. The primary symptoms include:

• Changes made in the Menuconfig are not reflected in the .config files after building the kernel.
• Users report that even after following the correct procedures, they do not see the expected configurations, particularly for GadgetFS.
• The issue arises during the kernel build process, specifically when users try to enable GadgetFS and subsequently build the kernel.

Relevant Specifications

• Hardware: Nvidia Jetson Orin Nano
• Software: Jetpack 6, Jetson Linux 36.3
• Users have varying levels of experience, with some being new to kernel customization.

Frequency and Impact

This issue appears to be consistent among multiple users, affecting their ability to customize and utilize GadgetFS effectively. The inability to reflect changes in the kernel configuration can significantly hinder development and deployment processes.

Possible Causes

Several potential reasons may contribute to this issue:

• Configuration Errors: Users may not be saving changes correctly in Menuconfig or may be using incorrect commands that do not apply their settings.

• Permissions Issues: Building the kernel in directories requiring root permissions could lead to improper configuration saves.

• Outdated Kernel Configurations: Certain configurations, such as GadgetFS, may be deprecated or not supported in the current version of the kernel being used (K5.15).

• Environmental Factors: Incorrect paths for source code or cross-compilers may lead to issues during the build process.

• User Errors: Misunderstandings regarding the build process or commands could lead to failures in applying configurations.

Troubleshooting Steps, Solutions & Fixes

To address these issues, follow these comprehensive troubleshooting steps:

1. Build Environment Setup:

   • Ensure that you extract the BSP source code into a directory where you have non-root permissions. For example:

     tar xf kernel_src.tbz2 -C ~/Downloads/kernel_src
     

2. Kernel Configuration:

   • Navigate to the source directory:

     cd ~/Downloads/kernel_src/kernel_jammy_source
     

   • Run make defconfig to set up default configurations.
   • Use make menuconfig to enable GadgetFS as built-in and save changes.

3. Building the Kernel:

   • Set up your cross-compiler environment variable:

     export CROSS_COMPILE=~/l4t-gcc/aarch64--glibc--stable-2022.08-1/bin/aarch64-buildroot-linux-gnu-
     

   • Build the kernel using:

     make -j$(nproc)
     

4. Flashing the Kernel:

   • After building, replace the kernel image in the boot directory of your Orin Nano.
   • If changes are still not reflected, consider reflashing the entire system as a last resort using:

     sudo ./tools/kernel_flash/l4t_initrd_flash.sh --external-device nvme0n1p1 \
       -c tools/kernel_flash/flash_l4t_t234_nvme.xml -p "-c bootloader/generic/cfg/flash_t234_qspi.xml" \
       --showlogs --network usb0 jetson-orin-nano-devkit internal
     

5. Loading Modules:

   • If GadgetFS is built as a module, load it using:

     sudo modprobe gadgetfs
     

6. Mounting GadgetFS:

   • To mount GadgetFS after it has been loaded:

     mkdir /mnt/gadgetfs
     sudo mount -t gadgetfs none /mnt/gadgetfs
     

Additional Recommendations

• If you continue to face issues with GadgetFS not appearing in your .config, check if it has been deprecated in your kernel version by consulting relevant documentation or forums.

• Regularly review and follow updates from Nvidia’s developer guides and community forums for any patches or changes related to kernel customization.

Unresolved Aspects

Some users have reported that despite following all steps, they still cannot mount GadgetFS or see expected configurations. Further investigation into specific error messages during mounting or additional logs may be necessary for resolution.