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Architectures and Processors forum Cortex-M33 - SVC call from non-secure code does not trigger non-secure SVC exception

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Cortex-M33 - SVC call from non-secure code does not trigger non-secure SVC exception

Michael Jung over 3 years ago

Hello,

I am trying to do a proof-of-concept running the Apache NuttX RTOS on STMicroelectronic's ST32L562E-DK board as the non-secure application with TrustedFirmware-M (ST's port of TF-M provided with STM32CubeL5). The ARM core on STM32L5xx MCUs is a Cortex-M33.

I can build, sign and flash NuttX as the non-secure application and TF-M boots into the RTOS initialization code. However, once the RTOS initialization code issues the first SVC instruction (to request an initial context switch to the 'init' task) the corresponding exception handler is not called (I do see systick exception handler calls, so generally the vector table seems to be set up correctly).

What could be the reason that an SVC instruction does not trigger the corresponding exception handler (both the SVC and the handler being in non-secure code)?

Any help is highly appreciated.

Thanks!

Michael