mjhjmtu

Can someone please, help me to understand this. I have read about it. But it's still confusing for me.

Memory maps allow pages to be "faded in" across multiple processes so that multiple processes can access them.
Explain how the operating system can handle this with paging?

The CPU has a memory management unit. It maps virtual memory address to physical memory addresses. It does this by looking up mappings in a table. These entries are cached in a translation lookaside buffer (TLB). Each process has its own mapping.

If two processes share some physical memory, then the OS will map part of process A's virtual memory to this physical memory, and map part of process B's virtual memory to this same physical memory. They do not have to be at the same virtual address in the two processes.

Virtual memory does not exist, therefore the name virtual. Virtual memory is just memory addresses (32 or 64 bit numbers) that the process sees and uses, and MAY point to real hardware memory.

The hardware memory it points to can be used already by another process, so sharing memory between processes is possible this way and this is done a lot.

There's also a mechanism that can detect process access to a specific virtual memory region, which can 'do stuff' right before you really access the address. It may map-in some hardware memory to that location for example, or kill your process for behaving badly.

This is all done with pages, blocks of address space that have a predefined function and size. The block-size is often fixed and may be from 1 to 16 kilobytes (depending on processor).