Is it possible to boot the Raspberry Pi in Secure Mode?

Question

I am currently developing a small OS on my Raspberry Pi, that I install by replacing the kernel.img file on the /boot partition of my SD card. By the time my code is run, the CPU is already in Normal Mode, so I can't have access to the Secure world / Trustzone area.

Is it possible to modify the boot process of the Raspberry to be able to start executing my code in Secure mode ?

Best, V.

Answer 1

In fact you don't have to do anything but stop being stupid like me. As explained here: https://raspberrypi.stackexchange.com/questions/14953/is-it-possible-to-boot-the-raspberry-pi-in-secure-mode

When the NS bit of the SCR register is 0, it means that you are in Secure Mode, which is the case at boot on my Raspberry. I had the meaning of this bit backwards, sorry !