As far as I've seen, the Secure Boot process is described like so: A firmware stored in read-only memory and therefore considered secure starts. It verifies the next software component (e.g. a bootloader), loads it and - if the check is successful - passes control to it. The bootloader is now responsible for verifying the integrity of the component after that and so on.
My question is, would it be possible for the firmware to do all the checks before passing control to each component? After the verification of the bootloader, instead of running it, could the firmware continue verifying other components in the system?
What if we have more than one core available and can run multiple verifications in parallel, would this be something that the firmware could handle, and if not why?