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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.
This increases the importance of caching values from intermediate levels of the host and guest page tables. It is also helpful to use large pages in the host page tables to reduce the number of levels (e.g., in x86-64, using 2 MB pages removes one level in the page table). Since memory is typically allocated to virtual machines at coarse ...
Supporting 64 bit addresses in the page-table is a significant change as this enables two changes to the processor addressing. Firstly, the page table walker, which uses physical addresses to access the page table and directory, can now access physical addresses greater than the 32-bit physical addresses supported in systems without PAE.
Unlike a true page table, it is not necessarily able to hold all current mappings. The operating system must be prepared to handle misses, just as it would with a MIPS-style software-filled TLB. The IPT combines a page table and a frame table into one data structure. At its core is a fixed-size table with the number of rows equal to the number ...
The entries in the page directory have an additional flag, in bit 7, named PS (for page size). This flag was ignored without PSE, but now, the page-directory entry with PS set to 1 does not point to a page table, but to a single large 4 MiB page. The page-directory entry with PS set to 0 behaves as without PSE.
existing instructions extended to a 64 bit address size (JRCXZ) existing instructions extended to a 64 bit operand size (remaining instructions) Most instructions with a 64 bit operand size encode this using a REX.W prefix; in the absence of the REX.W prefix, the corresponding instruction with 32 bit operand size is encoded. This mechanism also ...
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. [1]
These instructions were introduced in 6th generation Intel Core "Skylake" CPUs. The last CPU generation to support them was the 9th generation Core "Coffee Lake" CPUs. Intel MPX adds 4 new registers, BND0 to BND3, that each contains a pair of addresses.