what is the overhead in clock cycles for context switching inside the non-secured (non-secured thread and non-secured thread)
what is the overhead in clock cycles for context switching from the non-secured thread to secured thread ?
Is the answer different between M33 to M23?
You should be more specific what you mean with "context switch". In an OS a "context switch" means for example to save/restore registers, change the MMU/MPU and so on.
Sorry for not clarifying. I do mean context switch of two OS threads .
i.e if I have two threads which were created in the non-secured world, what is the overhead in clock cycle when the context switch between them occurs?
also, if I have two threads, one was created in a secured world and one in a non-secured world, what is the overhead in clock cycle when the context switch between them occurs?
Y.o.o said:orry for not clarifying. I do mean context switch of two OS threads .
Depends on the OS. Better ask in the forum for the OS you are using.
I am familiar with the overhead for regular OS context switching. I was wondering what is the TrustZone additional overhead since it introduce additional secure non-secure switching. My question is regarding the ARM v8 architecture and not os-dependent.
The Cortex-M23 TRM says: "branch And exchange Non-secure BXNS <Rm> 4"