作者Million

Even when PAE is enabled, only 4 GB of physical-address space can be addressed at any given time. Regardless of how big the page sizes are, only 32 bits of linear-address space are available. To address more than 4 GB of physical memory, CR3 must be changed (thus pointing to a different set of paging structures), or the existing paging structures must be modified (on-the-fly) by the operating system.

所以被我猜對了!

要存取超過4G-- 1.CR3必須變更位址(這OS才有辦法做吧!) or 2.已存在的PAGE架構必須由OS快速地變更.