I am writing a function which sets a binary semaphore, calls a hardware interupt, then in the handler must free the semaphore. Correct me if I am wrong but I should re-write vApplicationIRQHandler provided by my port, and documented here. I replaced InterruptHandlerFunctionTable[ ulInterruptID ](); with the function which frees the semaphore. Additionally, I attempt to call __asm volatile ( “SWI 0” ::: “memory” ); to reach the IRQ handler but it is never reached. Can anyone help or provide documentation on the Cortex A9 that better specifies how to call a harware intrupt and then handle it as I cannot seem to find this? Thanks.

As I recall….

I replaced InterruptHandlerFunctionTable ulInterruptID ; with the

….these handlers handle IRQ interrupts, whereas this

__asm volatile ( “SWI 0” ::: “memory” ); to reach the IRQ handler but it

generates a supervisor call (SVC as was) interrupt, i.e. not an IRQ interrupt hence it won’t be handled by InterruptHandlerFunctionTable[]. https://developer.arm.com/docs/den0024/latest/aarch64-exception-handling However according to the link you posted there is already and SVC handler installed which is called FreeRTOSSWIHandler, and looking at the code for that (which is in FreeRTOS/Source/portable/GCC/ARMCA9/portASM.S) it is currently hard coded as a yield function as it doesn’t check the SVC number, but instead just assumes SVC is not used for anything other than yielding. So currently when you call SWI 0 you are just requesting a context switch, not calling your handler. You can update FreeRTOSSWI_Handler() to test the SVC/SWI number, and the call something different depending on the number.