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The page table structure used by x86-64 CPUs when operating in long mode further extends the page table hierarchy to four or more levels, extending the virtual address space, and uses additional physical address bits at all levels of the page table, extending the physical address space.
A page table is a data structure used by a virtual ... typically look up the address mapping in the page table to see ... off-chip extension of the TLB ...
Intel 5-level paging, referred to simply as 5-level paging in Intel documents, is a processor extension for the x86-64 line of processors. [1]: 11 It extends the size of virtual addresses from 48 bits to 57 bits by adding an additional level to x86-64's multilevel page tables, increasing the addressable virtual memory from 256 TiB to 128 PiB.
By treating each guest-physical address as a host-virtual address, a slight extension of the hardware used to walk a non-virtualized page table (now the guest page table) can walk the host page table. With multilevel page tables the host page table can be viewed conceptually as nested within the guest page table. A hardware page table walker ...
Those machines, and subsequent machines supporting memory paging, use either a set of page address registers or in-memory page tables [d] to allow the processor to operate on arbitrary pages anywhere in RAM as a seemingly contiguous logical address space. These pages became the units exchanged between disk and RAM.
The architecture permits extending this to 52 bits in the future [11]: 24 [20] (limited by the page table entry format); [11]: 131 this would allow addressing of up to 4 PiB of RAM. For comparison, 32-bit x86 processors are limited to 64 GiB of RAM in Physical Address Extension (PAE) mode, [21] or 4 GiB of RAM without PAE mode. [11]: 4
The page attribute table (PAT) is a processor supplementary capability extension to the page table format of certain x86 and x86-64 microprocessors. Like memory type range registers (MTRRs), they allow for fine-grained control over how areas of memory are cached , and are a companion feature to the MTRRs.
An overhead of 1 KiB of memory is required for maintaining page directories and page tables. When accessing this 1 MiB memory, each of the 256 page entries would be cached in the translation lookaside buffer (TLB; a cache that remembers virtual address to physical address translations for faster lookup on subsequent memory requests). Cluttering ...