Hi,

There is no forwarded define for '__START' in the current TF-M design, then the runtime init provided by toolchain is applied. This runtime init did something unnecessary as the data copying and ZI has been done already by the startup code, jumping to spm::main would be the next job as SPM would prepare runtime environment for subsequent partition execution and itself won't need other runtime operations besides the data moving.

I have created a patch to jump to main under GNUARM:

https://review.trustedfirmware.org/c/TF-M/trusted-firmware-m/+/5609

Change the code is because this would easy the code reading --  most of the users won't check a  compiler flag given in the build system for forwarding '__START', so they will try to find the __start from the toolchain source.

Currently, we can not avoid depending on ARMCLANG runtime init, so need double check (also IAR).

Please provide your feedback, we are changing the platform startup code and need your confirmation to see if it is applicable.

Best Regards,

Summer