Zephyr: MIMXRT1180-EVK dual-core system where CM33 boots first and then starts CM7

[ruchi-30]

What I am trying to do ?

• Run Zephyr on CM33 as the primary/boot core
• Start CM7 from CM33 after system initialization
• Eventually run all real-time tasks on CM7

What I have tried so far?

1. Independent image builds
   Built Zephyr images separately for:

• mimxrt1180_evk/mimxrt1189/cm33
• mimxrt1180_evk/mimxrt1189/cm7

2. Manual CM7 image loading

• Converted the CM7 ELF to a raw binary
  Embedded the CM7 binary into the CM33 application (via object file / blob)

• From CM33:
  Enabled CM7 clock
  Copied the CM7 image into CM7 ITCM/OCRAM
  Executed DSB/ISB barriers
  Released CM7 from reset using SRC registers

• Observed behavior
  CM33 runs correctly and prints logs
  CM33 confirms CM7 clock enable, image copy, and CM7 release

However, there is no observable execution on CM7 (no UART output / GPIO activity)

Additional issue

I also attempted to use west build --sysbuild to build the primary (CM33) and child (CM7) images together, but I am currently unable to get the child image to build successfully on MIMXRT1180.

[DerekSnell]

Hi @ruchi-30 ,
There are a few dual-core examples already in the Zephyr repo which run on the MIMXRT1180-EVK and demonstrate the CM33 launching the CM7 core. Some of these examples include mbox, mbox_data, and OpenAmp. The MIMXRT1180-EVK board page gives this build command as an example for the mbox sample:

west build -b mimxrt1180_evk/mimxrt1189/cm33 samples/drivers/mbox --sysbuild

That command leverages Sysbuild to build both images for CM33 and CM7. West will also flash both images with the west flash command.

Launching the CM7 core requires selecting CONFIG_SECOND_CORE_MCUX=y for the CM33 image, which is used in these dual-core samples like mbox. Once the CM33 image is flashed and it launches the CM7, you can load other samples for the CM7. For example, this command builds blinky for the CM7

west build -b mimxrt1180_evk//cm7 samples/basic/blinky --pristine

Let us know how that works for you.

[ruchi-30]

I am able to build the images for both core but when I am flashing the image , I am not getting any print statement or log message on UART. I am not using mbox as we only need CM33 for booting CPU CM7 then we want to run application program on CM7

[ruchi-30]

Current Status

• Standalone CM33 Zephyr image runs correctly
• Sysbuild successfully generates the CM33 (parent) image
• CM7 child image is built, but does not execute at runtime

Runtime Behavior

• CM33 boots and continues execution
• CM7 shows no observable activity: No LED toggle , No UART output
• No clear indication that CM7 is released from reset or reaches its reset vector

Questions

1. Is sysbuild officially supported and validated for RT1180 dual-core (CM33 → CM7) in Zephyr v4.2 or we need to upgarde the zephyr version?
2. Are there known gaps or limitations in sysbuild for RT1180 (e.g. CM7 reset vector setup, memory placement, or handoff mechanism)?
3. Is there a reference or internal example for RT1180 sysbuild-based CM33→CM7 boot (similar to MCUX MCMGR-based multicore examples)?

Any guidance on the expected boot flow for CM7 when using sysbuild on RT1180 would be appreciated.

Thanks,
Ruchi

[DerekSnell]

Hi @ruchi-30 ,

I just tested the mbox sample on the MIMXRT1180-EVK using the build command below, and the sample with Sysbuild works great in v4.3.0 and v4.2.0 and the latest main branch with b4108b5 .

west build -b mimxrt1180_evk//cm33 samples/drivers/mbox --sysbuild --pristine
west flash

NXP already provides a few multicore sample apps running on this evaluation board, leveraging Sysbuild to simplify the examples. I understand you will not use the mbox driver in your app. But I recommend you start with a known good example like mbox. Verify this runs as expected on your hardware. Then you can copy that app and remove what you want. If you still have issues, you can compare the app with issues to the working reference to find what is different.

To answer your questions:

1. Is sysbuild officially supported and validated for RT1180 dual-core (CM33 → CM7) in Zephyr v4.2 or we need to upgarde the zephyr version?

Sysbuild works with the mbox sample for me in v4.2.0. However, there were multiple improvements for RT1180 multicore and CM7 execution afterwards, so I recommend starting with the latest release v4.3.0.

2. Are there known gaps or limitations in sysbuild for RT1180 (e.g. CM7 reset vector setup, memory placement, or handoff mechanism)?

Not that I am aware of. Start with the known good examples listed above.

3. Is there a reference or internal example for RT1180 sysbuild-based CM33→CM7 boot (similar to MCUX MCMGR-based multicore examples)?

Yes, the mbox and other multicore samples shared above.

Any guidance on the expected boot flow for CM7 when using sysbuild on RT1180 would be appreciated.

I recommend you flash a working example like mbox, confirm it works on your hardware. Then you can use a debugger and step through second_core_boot() in soc.c to see how the CM33 app launches the CM7 core.

Let us know how that works for you.

[ruchi-30]

Thank you so much for help !! I am now able to get it running.