Issues Building Custom Kernel 36.4 for Jetson Orin Nano Dev Kit

Issue Overview

Users are experiencing difficulties when attempting to build a custom kernel for the Nvidia Jetson Orin Nano Developer Kit 8GB using JetPack 6.1 (Linux for Tegra 36.4). The main symptoms include:

• The output kernel image is smaller than expected (29MB) even when enabling additional modules
• Compilation errors occur for the "nvidia-oot" module, specifically:
  • "clk/tegra/clk-bpmp.c:673:5: error: redefinition of ‘tegra_bpmp_init_clocks’"
  • "/reset/tegra/reset-bpmp.c:67:5: error: redefinition of ‘tegra_bpmp_init_resets’"
• These issues persist when using different build methods, including native compilation on the device, cross-compilation with SDK Manager, and using various build scripts

Possible Causes

1. Incorrect build process or environment setup
2. Incompatibility between custom kernel configurations and Nvidia’s proprietary drivers
3. Conflicts in header files or function definitions related to the Tegra bootloader power management processor (BPMP)
4. Issues with the toolchain or build dependencies

Troubleshooting Steps, Solutions & Fixes

1. Ensure proper setup of the build environment:

   • Download the correct JetPack kernel sources:

     wget https://developer.nvidia.com/downloads/embedded/l4t/r36_release_v4.0/sources/public_sources.tbz2
     

   • Install necessary dependencies:

     sudo apt install wget lbzip2 build-essential bc zip libgmp-dev libmpfr-dev libmpc-dev vim-common libncurses-dev bison flex libssl-dev libelf-dev
     

2. Set up the build directory and extract sources:

   cd ~/nvidia/nvidia_sdk/JetPack_6.1_Linux_JETSON_ORIN_NANO_TARGETS/Linux_for_Tegra
   tar -xjf public_sources.tbz2 Linux_for_Tegra/source/kernel_src.tbz2 --strip-components 2 
   tar -xjf public_sources.tbz2 Linux_for_Tegra/source/kernel_oot_modules_src.tbz2 --strip-components 2 
   tar -xjf public_sources.tbz2 Linux_for_Tegra/source/nvidia_kernel_display_driver_source.tbz2 --strip-components 2
   

3. Set environment variables:

   export DEVDIR=~/nvidia/nvidia_sdk/JetPack_6.1_Linux_JETSON_ORIN_NANO_TARGETS/Linux_for_Tegra
   export CROSS_COMPILE=$HOME/l4t-gcc/aarch64--glibc--stable-2022.08-1/bin/aarch64-buildroot-linux-gnu-
   export INSTALL_MOD_PATH=$DEVDIR/rootfs/
   export KERNEL_HEADERS=$DEVDIR/sources/kernel/kernel-jammy-src
   

4. Create and populate the sources directory:

   cd $DEVDIR
   mkdir sources 
   tar -xjf kernel_src.tbz2 -C sources
   tar -xjf kernel_oot_modules_src.tbz2 -C sources 
   tar -xjf nvidia_kernel_display_driver_source.tbz2 -C sources
   

5. Configure and build the kernel:

   cd $DEVDIR/sources/kernel/kernel-jammy-src
   make menuconfig
   cd $DEVDIR/sources
   make -C kernel
   sudo -E make install -C kernel
   

6. Build and install device tree and modules:

   make dtbs
   cp nvidia-oot/device-tree/platform/generic-dts/dtbs/* $DEVDIR/kernel/dtb/
   make modules
   sudo -E make modules_install
   

7. If custom kernel configurations are causing issues, try building with the default configuration first, then gradually add your custom changes while testing for errors after each modification.

8. Pay attention to warnings during the build process, especially those related to symbol definitions and module dependencies. Address these warnings if possible, as they may lead to runtime issues.

9. If errors persist, carefully review your custom kernel configurations to ensure they don’t conflict with Nvidia’s proprietary drivers or BPMP-related functions.

10. Consider using a clean build environment for each attempt, as residual files from previous builds may cause conflicts.

11. If the issue persists after following these steps, consider reaching out to Nvidia’s developer support or community forums with detailed logs and information about your specific custom kernel requirements.