Later versions of the ARM architecture, using the LDREX/STREX instruction family, use "Exclusive Monitors" for inter-processor synchronisation of Shared Memory. How are these Monitors ("Local" amd " Global") implemented? Silicon? Special Register? Firmware?
There is a local monitor as part of each core. The global monitor is usually implemented as part of the memory system. It could be a separate component, or integrated as part of the interconnect or memory controller.