@KenLSoft Yes, our platform (LPC55S69 by NXP) does defined __FPU_PRESENT=1U.

We are currently pre-occupied with the 5.12 release, you can look at Mbed-os PR#10027 to see how we solved this issue.

Can you elaborate on the root cause?

Inside the svc_handler if you check LR, which holds EXC_RETURN.

We are experiencing this issue on the NXP LPC55S69 MCU, which is Cortex-M33-FE core.

Opened https://developer.trustedfirmware.org/T273

Hi all,

I can verify that https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/653/ works on our code.

I can verify that https://review.trustedfirmware.org/#/c/trusted-firmware-m/+/627/ works on our code.

We will verify it on our Musca_a1 mbed-os porting work and update the results.

A workaround for us which fixed this issue was setting the descriptor struct volatile:

volatile struct tfm_sfn_req_s desc;
struct tfm_sfn_req_s *desc_ptr = &desc;

Should I close this issue and move this question here: https://developer.trustedfirmware.org/ponder/?