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# QNX Support Request: Raspberry Pi Compute Module 5 Display Support

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sw7ft edited this page Nov 11, 2025 · 1 revision

Date: November 11, 2025
QNX Version: 8.0.0
Hardware: Raspberry Pi Compute Module 5 (CM5)
Display: HyperPixel 4 Square (720x720 DPI display)
Issue: Display output not working on CM5, but works on regular Raspberry Pi 5

Background

We're working on getting a display working on the Raspberry Pi Compute Module 5 running QNX 8.0. The same QNX image works perfectly on a regular Raspberry Pi 5 with display output, but on the CM5 we're hitting a hardware detection issue.

Why It Works on Regular Pi 5 but Not CM5

Here's the simple breakdown:

Regular Raspberry Pi 5:

  • QNX startup code recognizes it as "RaspberryPi5" (it's in the hardware lookup table)
  • Startup creates the required GPU devices: /dev/vcio and /dev/smmuman
  • DRM driver starts successfully
  • GPU initializes properly
  • Display works! ✅

Raspberry Pi Compute Module 5:

  • QNX startup code doesn't recognize it (CM5 not in the hardware lookup table)
  • Hardware is detected as "Unknown"
  • Startup skips creating /dev/vcio and /dev/smmuman (only creates them for recognized hardware)
  • DRM driver can't access the GPU without these devices
  • Display doesn't work ❌

What we've tried:

  • We successfully patched the drm-rpi5 binary to bypass the hardware type check
  • The driver now runs without crashing, but still can't initialize the GPU because the required devices don't exist
  • The root issue is in the IFS startup code, which only creates vcio/smmuman for recognized Pi models

Questions for QNX Support Team

1. Official CM5 Support

Does QNX 8.0 BSP officially support the Raspberry Pi Compute Module 5? If not, is this something that's planned for a future release? What would the timeline look like?

2. Hardware Detection

The CM5 is currently being detected as "Unknown" hardware type. Is there a way to add CM5 hardware revision codes to the BSP's hardware lookup table? If so, what specific revision codes should be added, and is there a patch or workaround available?

3. Device Creation Workaround

The startup code in the IFS doesn't create /dev/vcio and /dev/smmuman for "Unknown" hardware. Is there a way to:

  • Get a modified startup binary that creates these devices for CM5?
  • Get access to the startup source code so we can modify it ourselves?
  • Get guidance on how to properly patch the IFS to enable this?

4. Display Configuration

We're specifically trying to get a HyperPixel 4 Square display (720x720 DPI) working. The device tree overlay vc4-kms-dpi-hyperpixel4sq exists in the boot partition, but it requires DRM/GPU initialization to work. What's the recommended path forward for getting DPI displays working on CM5?

5. Manual Device Creation

We've successfully patched drm-rpi5 to bypass hardware checks, and the driver stays running. However, it still can't initialize because /dev/vcio and /dev/smmuman don't exist. Is there a way to manually create these devices, or do we absolutely need to modify the IFS startup code?

6. Beta/Test Support

Would it be possible to get:

  • The specific CM5 hardware revision codes that should be added to the lookup table?
  • A modified IFS with CM5 support (even if it's beta/test quality)?
  • Source code access for the startup binary so we can make the modifications ourselves?

7. Documentation and Process

Is there official documentation or a support process for adding new hardware variants to the QNX BSP? We'd be happy to contribute our findings back to help with CM5 support if there's a process for that.

Technical Details (For Reference)

Current System State:

  • QNX 8.0 boots successfully on CM5
  • Network (SSH) works fine
  • drm-rpi5 binary has been patched to bypass hardware type check
  • Driver process runs (21 threads active) but can't initialize GPU
  • Missing devices: /dev/vcio, /dev/smmuman
  • No /dev/dri/card0 created

Hardware Detection:

  • CM5 detected as: "Unknown"
  • Expected: "RaspberryPi5" (same as regular Pi 5)
  • Issue: Hardware lookup table in IFS startup doesn't include CM5 revision codes

Files Modified:

  • /system/bin/drm-rpi5 - Patched to bypass hardware check (2 patches applied)
  • Patches force Pi5 initialization path and return success instead of error

Investigation Files Available: We have comprehensive investigation documentation including:

  • Full hardware detection analysis
  • Binary patching details
  • System logs and diagnostics
  • HyperPixel display requirements

What We're Hoping For

Ideally, we'd like to get the HyperPixel 4 Square display working on the CM5. The hardware is essentially the same as a regular Pi 5, just in a different form factor, so we're hoping there's a relatively straightforward way to enable support.

We understand that CM5 might not be officially supported yet, but any guidance or workarounds you can provide would be greatly appreciated. We're also happy to test beta builds or provide feedback if that would be helpful.

Thank you for your time and assistance!

Contact Information: [Your name/email/company]

Attachments:

  • QNX_CM5_HyperPixel_Investigation.md (full technical investigation)
  • QNX_CM5_BINARY_PATCH_STATUS.md (binary patching details)
  • System logs and diagnostics (available upon request)

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