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In computing, Physical Address Extension (PAE), sometimes referred to as Page Address Extension, [1] is a memory management feature for the x86 architecture. PAE was first introduced by Intel in the Pentium Pro , and later by AMD in the Athlon processor. [ 2 ]
Compared to the Physical Address Extension (PAE) method, PSE-36 is a simpler alternative to addressing more than 4 GB of memory. It uses the Page Size Extension (PSE) mode and a modified page directory table to map 4 MB pages into a 64 GB physical address space. PSE-36's downside is that, unlike PAE, it doesn't have 4-KB page granularity above ...
AMD64 (also variously referred to by AMD in their literature and documentation as “AMD 64-bit Technology” and “AMD x86-64 Architecture”) was created as an alternative to the radically different IA-64 architecture designed by Intel and Hewlett-Packard, which was backward-incompatible with IA-32, the 32-bit version of the x86 architecture.
The 32-bit PAE desktop kernel (linux-image-generic-pae) in Ubuntu 9.10 and later, also provides the PAE mode needed for hardware with the NX CPU feature. For systems that lack NX hardware, the 32-bit kernels now provide an approximation of the NX CPU feature via software emulation that can help block many exploits an attacker might run from ...
Many 32-bit computers have 32 physical address bits and are thus limited to 4 GiB (2 32 words) of memory. [3] [4] x86 processors prior to the Pentium Pro have 32 or fewer physical address bits; however, most x86 processors since the Pentium Pro, which was first sold in 1995, have the Physical Address Extension (PAE) mechanism, [5]: 445 which allows addressing up to 64 GiB (2 36 words) of memory.
The NX bit (no-execute) is a technology used in CPUs to segregate areas of a virtual address space to store either data or processor instructions. An operating system with support for the NX bit may mark certain areas of an address space as non-executable. The processor will then refuse to execute any code residing in these areas of the address ...
It was mentioned that creating a page table structure that contained mappings for every virtual page in the virtual address space could end up being wasteful. But, we can get around the excessive space concerns by putting the page table in virtual memory, and letting the virtual memory system manage the memory for the page table.
A few computers have a main memory larger than the virtual address space of a process, such as the Magic-1, [34] some PDP-11 machines, and some systems using 32-bit x86 processors with Physical Address Extension. This nullifies a significant advantage of paging, since a single process cannot use more main memory than the amount of its virtual ...