This is nothing like DOS extended memory. It is quite similar to Intel PAE, allowing more than 4GB of physical memory. Each process has the usual 4GB virtual

This is nothing like DOS extended memory. It is quite similar to Intel PAE, allowing more than 4GB of physical memory. Each process has the usual 4GB virtual address space; the MMU simply maps it into pages taken from a larger pool. It makes perfect sense when running multiple large processes or doing virtualisation.