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Extended Feature Enable Register (EFER) is a model-specific register added in the AMD K6 processor, to allow enabling the SYSCALL/SYSRET instruction, and later for entering and exiting long mode. This register becomes architectural in AMD64 and has been adopted by Intel as IA32_EFER.
The Linux kernel includes full PAE-mode support starting with version 2.3.23, [24] in 1999 enabling access of up to 64 GB of memory on 32-bit machines. A PAE-enabled Linux kernel requires that the CPU also support PAE. The Linux kernel supports PAE as a build option and major distributions provide a PAE kernel either as the default or as an option.
If paging is not enabled, these linear addresses are the same as physical addresses. Note that when paging is enabled, different tasks may have different linear-to-physical address mappings. When this is the case, an address in a debug address register may be relevant to one task but not to another.
In computing, protected mode, also called protected virtual address mode, [1] is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as segmentation, virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software.
With hardware TLB management, the CPU automatically walks the page tables (using the CR3 register on x86, for instance) to see whether there is a valid page-table entry for the specified virtual address. If an entry exists, it is brought into the TLB, and the TLB access is retried: this time the access will hit, and the program can proceed ...
Moves to the CR3 control register are serializing and will flush the TLB. [l] On Pentium and later processors, moves to the CR0 and CR4 control registers are also serializing. [m] MOV reg,DRx: 0F 21 /r [j] Move from x86 debug register to general register. [k] MOV DRx,reg: 0F 23 /r [j] Move from general register to x86 debug register. [k]
When pure demand paging is used, pages are loaded only when they are referenced. A program from a memory mapped file begins execution with none of its pages in RAM. As the program commits page faults, the operating system copies the needed pages from a file, e.g., memory-mapped file, paging file, or a swap partition containing the page data ...
In computing, a page fault is an exception that the memory management unit (MMU) raises when a process accesses a memory page without proper preparations. Accessing the page requires a mapping to be added to the process's virtual address space.