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i.MX93 board caveats

The Remoteproc driver for i.MX93 has some limitations. Workarounds may be needed in case of unexpected issues. Below are troubleshooting guidelines for common problems.

My board stops responding when I start the M-class core using Remoteproc

Example: How to reproduce

  1. Copy your-firmware.elf to /lib/firmware on the board.
  2. Use the Remoteproc framework to load the firmware:
echo your-firmware.elf > /sys/class/remoteproc/remoteproc0/firmware
echo start > /sys/class/remoteproc/remoteproc0/state
  1. The board becomes unresponsive (neither UART responds).

How to fix

Various sources (NXP docs, NXP forum, fs-net forum) indicate that you must boot the M-class core before starting the program. This is done from the U-Boot menu (press any key over UART during boot):

u-boot=> run prepare_mcore
u-boot=> boot

After performing this step, retry the above steps or your Docker run. The board should not lock up, and the firmware should load successfully.

Note: This pre-boot step is not required for example programs built with MCUXpresso SDK, such as baremetal-hello-world.elf or freertos-counter.elf.

NULL Pointer Dereference Error from Remoteproc Driver

A common cause of this issue is that your firmware does not include a resource table. The following example demonstrates the difference between firmware with and without a resource table, and how it affects Remoteproc operation.

Example: How to reproduce

  1. Copy both your-firmware-with-resource-table.elf and your-firmware-without-resource-table.elf to /lib/firmware on the board.
  2. Load each firmware using the Remoteproc framework:
echo your-firmware-with-resource-table.elf > /sys/class/remoteproc/remoteproc0/firmware
echo start > /sys/class/remoteproc/remoteproc0/state
# ... wait ...
echo stop > /sys/class/remoteproc/remoteproc0/state
# ... wait ...
echo your-firmware-without-resource-table.elf > /sys/class/remoteproc/remoteproc0/firmware
echo start > /sys/class/remoteproc/remoteproc0/state
  1. Observe the following error on the Linux host:
NULL pointer dereference at virtual address 0000000000000000

Remoteproc becomes unresponsive:

can't lock rproc imx-rproc: -4

How to fix

Ensure your firmware always contains a resource table.

You can verify this by running:

readelf -S your-firmware.elf

Check for a .resource_table section in your ELF file. If it is missing, your firmware may not work with Remoteproc on the i.MX93 board.

Tip: Most RTOSes and SDKs (e.g., MCUXpresso, FreeRTOS) generate a resource table automatically when RPMsg or Remoteproc support is enabled. For bare-metal or custom firmware, you must manually define and place a resource table in your code. Refer to NXP documentation for details.