SW4STM32 and SW4Linux fully supports the STM32MP1 asymmetric multicore Cortex/A7+M4 MPUs

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world. And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4.
You can get more information from the ac6-tools website and download (registration required) various documents highlighting:

System Workbench for STM32

You are viewing a reply to Mbed project debug fails.  

Mbed project debug fails.

As it’s crashing in the startup code, put a breakpoint in that assembly (startup_stm32.s) on the first instruction after “Reset_Handler:” and try stepping through it.

I’d also look at the *.map file to see what was linked. Equivalent information is available by expanding the *.elf program in the Project Explorere view if the elf Binary Parser is installed and enabled.

The default_handler will catch a lot of interrupts so very hard to determine the cause.