about global monitor

Hi all:

  I have read some articles about exclusive instructions in ARM64. There is a simple soc logic diagram in one article, which is as follows.

multi-core processor is running linux and the other single processor is running rtos. Both linux and rtos have separate physical memory space.

It says that exclusive access to a spinlock(using ldxr, stxr) in linux just reqires the participation of local monitor and the cache coherency logic, but not the global monitor.

I doubt that since a spinlock variable in memory is shareable.

Can someone give me a hand to clarify it?

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