Hello,
I would like to switch from EL1 to EL0 and update my PC in one instruction because I would like to prevent code execution in EL0 mode in my supervisor memory zone.
In order to do that I would like to use ERET instruction or to pop CPSR from stack at boot time instead of using CPS instruction.
I didn't find in the documentation a specific reason to not use ERET at boot time but when I am using it (or when i amp poping cpsr from stack "pop pc^") the behavior is erroneous.
Thanks by advance,
Kevin
yes! I am on a R52. Did you know the explanation on what is going on?
I have no experience with Armv8-R, but on Armv7-R I just make a "refia sp!" to switch to EL0. Are you sure you are not in EL2? You say "directly after boot", so I'd assume the core boots in EL2.
I am doing a first eret to jump to el1, then i am loading lrand spsr to do a second eret. After this point the software become unstable. Another company (which is specialized in rtos) has encountered the same problem. We will ask the manufacturer. If you are interested i can forward you the answers. For the moment i trig an hvc as a workaround.
Sure, though I haven't seen the r52 in the wild (guess it is an automotive chip), you can PM me the outcome. I am a hunter and collector of such infos.