Building Jetson Orin Nano Dev Board Images Without a Connected Board

Issue Overview

Some users have reported difficulties when attempting to build images for the Nvidia Jetson Orin Nano Dev Board without having a physical board connected to the system. The specific issue arises when using the flash.sh script (which is actually responsible for both building and flashing the image) in this scenario.

The script fails to respect the RAMCODE_ID environment variable and instead relies on a chip_info.bin_bak file if it exists. This file is created and persists when a board has been previously connected, and if the RAMCODE_ID in this file doesn’t match the intended board version, it results in the generation of an incorrect mem_rcm.bct file.

The impact of this issue is not fully clear, as it depends on the specific flashing methods and paths used. However, it can lead to complications and broken builds when attempting to create images for boards that are not physically connected, especially in automated or CI environments.

Possible Causes

1. Script Naming Confusion: The flash.sh script is misnamed, as it handles both building and flashing functionalities, which can lead to misunderstandings about its purpose and behavior.

2. Persistent chip_info.bin_bak File: The script prioritizes the chip_info.bin_bak file if it exists, even if the RAMCODE_ID environment variable is set. This file is created when a board has been previously connected and is not automatically cleaned up, causing the script to use potentially outdated or mismatched information.

3. Inconsistent Handling of RAMCODE_ID: The script does not consistently respect the RAMCODE_ID environment variable across all relevant parts of the build process, leading to discrepancies in the generated files.

4. Lack of Clear Documentation: There may be insufficient documentation or examples demonstrating the proper setup and usage of environment variables when building images without a connected board.

Troubleshooting Steps, Solutions & Fixes

1. Apply the Provided Patch:

   • Open the bootloader/tegraflash_impl_t234.py file in a text editor.
   • Locate the tegraflash_get_ramcode function.
   • Add the following lines before the existing code block:

     if os.environ.get('RAMCODE_ID') is not None:
         ramcode = int(os.environ['RAMCODE_ID'].replace(':', ''), 16) >> 2
     

   • Save the modified file.

   This patch ensures that the script prioritizes the RAMCODE_ID environment variable if it is set, rather than relying solely on the chip_info.bin_bak file.

2. Set Required Environment Variables:

   • Before running the flash.sh script, ensure that the following environment variables are properly set based on your target board configuration:
     • BOARDID
     • BOARDSKU
     • FAB
     • BOARDREV
     • RAMCODE_ID
   • Refer to the provided environment variables value table for the correct values corresponding to your specific board model.

3. Clean Up chip_info.bin_bak File (if necessary):

   • If you have previously connected a board with a different configuration, the chip_info.bin_bak file may contain outdated information.
   • Locate and delete the chip_info.bin_bak file to ensure that the script relies solely on the provided environment variables.

4. Use Explicit Build and Flash Scripts (if available):

   • If your setup includes separate scripts for building and flashing, consider using them instead of the combined flash.sh script.
   • This can help avoid potential issues related to the dual functionality of flash.sh and provide more control over the build process.

5. Document and Share Best Practices:

   • If you develop a reliable workflow for building images without a connected board, consider documenting and sharing it with the community.
   • Include clear instructions on setting up the required environment variables, any necessary patches or modifications, and any potential gotchas or limitations.

By applying the provided patch, setting the appropriate environment variables, and following the recommended troubleshooting steps, users should be able to successfully build images for the Nvidia Jetson Orin Nano Dev Board without requiring a physical board to be connected during the build process. However, it’s important to note that this issue may have additional implications or edge cases that require further investigation and testing.