Typical time to boot to display with Secure Boot enabled

Technical Support
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Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

Based on the available documentation, I can provide some insights about boot times and display initialization, though specific timing data for secure boot scenarios with iMX8MP/iMX95 is limited in the sources.

Boot Time Reference Points

The documentation mentions that Toradex has achieved impressive boot performance in the past. For context, the Windows Embedded Compact operating system for the Colibri T20 module was able to cold boot in 480 milliseconds(1). This demonstrates Toradex’s focus on boot optimization through techniques like cache performance improvements and concurrent driver loading(1).

Display Initialization Challenges

From community discussions, there are known challenges with early display initialization. One user reported that with a MIPI display using a custom driver on iMX8MM, the display driver probe occurred at 6.49 seconds into boot, but driver enable didn’t happen until 40 seconds when containers started(2). This suggests that without optimization, display initialization can be significantly delayed.

Secure Boot Implementation

The documentation shows that Toradex supports secure boot implementation on iMX8MP using the tdx-signed inherit class and various HAB (High Assurance Boot) configuration parameters(3):

INHERIT += "tdx-signed"
TDX_IMX_HAB_ENABLE = "1"
UBOOT_SIGN_ENABLE = "1"

(3)

The secure boot process involves signing the U-Boot bootloader binary, and enforcement only occurs after fuses are set on the device(3).

Optimization Approaches

For early display output, the documentation suggests:

  1. Initramfs Customization: Using tools like ostree-customize-plymouth.sh to add splash screens to the initramfs for very early boot display(2)

  2. TorizonCore Builder: Creating custom images with optimized boot sequences and driver initialization(2)

  3. Plymouth Integration: TorizonCore uses Plymouth for splash screen management, which is initiated from initramfs early during boot(2)

Current Limitations

The available sources don’t provide specific boot time benchmarks for iMX8MP or iMX95 with secure boot enabled. The timing will depend on factors like:

  • Secure boot verification overhead
  • Display driver complexity
  • Initramfs size and content
  • Hardware-specific initialization requirements

For precise timing data and hardware-specific optimizations for your use case, you may need to conduct testing with your specific configuration.

Best regards, Toradex AI Assistant.

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