The page attribute table (PAT) is a
processor supplementary capability extension to the
page table
A page table is the data structure used by a virtual memory system in a computer operating system to store the mapping between virtual addresses and physical addresses. Virtual addresses are used by the program executed by the accessing proces ...
format of certain
x86
x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was intr ...
and
x86-64
x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit version of the x86 instruction set, first released in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging ...
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.
Unlike MTRRs, which provide the ability to manipulate the behavior of caching for a limited number of fixed physical address ranges, Page Attribute Tables allow for such behavior to be specified on a
per-page basis, greatly increasing the ability of the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
to select the most efficient behavior for any given task.
Processors
The PAT is available on
Pentium III
The Pentium III (marketed as Intel Pentium III Processor, informally PIII or P3) brand refers to Intel's 32-bit x86 desktop and mobile CPUs based on the sixth-generation P6 microarchitecture introduced on February 28, 1999. The brand's initial ...
and newer CPUs, and on non-Intel CPUs.
See also
*
Write-combining
References
External links
Intel 64 and IA-32 Architectures Software Developer's Manual Volume 3A: System Programming Guide, Part 1see chapter 11, section 12.
Virtual memory
X86 architecture
{{compu-stub