Rasberry Pi 4B regression since 2.1.0 #401
Description
RPi4B does not use PSCI and instead has BCM firmware for doing CPU bring-up.
This means single-core and SMP configurations of the RPi4B don't work right now.
The single-core case is easy to fix by just commenting out the section of the Microkit loader that reads PSCI_VERSION.
The SMP case is a bit more involved by using the BCM spin table method for bringing up additional CPUs instead of PSCI.
Really need to start having CI hardware runs to prevent basic issues like this.