From Operating System theory, OS implements a pagetableentry, PTE, to describe a mapping of a page in VAS to physical page.
来自操作系统的理论，操作系统引入一个页表项，PTE，描述了一个在VAS中的页到物理页的映射。
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Each entry in the PTE chain USES 4 bytes to store a pointer to the page-tableentry and an additional 4 bytes to store the pointer to the next entry on the chain.