Search results
Results from the WOW.Com Content Network
However, "client" versions of 32-bit Windows (Windows XP SP2 and later, Windows Vista, Windows 7) limit physical address space to the first 4 GB for driver compatibility [16] even though these versions do run in PAE mode if NX support is enabled.
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.
Limits on physical memory for 32-bit platforms also depend on the presence and use of Physical Address Extension (PAE), which allows 32-bit systems to use more than 4 GB of physical memory. PAE and 64-bit systems may be able to address up to the full address space of the x86 processor.
PAE paging translates 32-bit linear addresses to 52-bit physical addresses. 1 Although 52 bits corresponds to 4 PBytes, linear addresses are limited to 32 bits; at most 4 GBytes of linear-address space may be accessed at any given time.
This allows a large page to be located in 36-bit address space. If Physical Address Extension (PAE) is used, the size of large pages is reduced from 4 MiB down to 2 MiB, and PSE is always enabled, regardless of the PSE bit in CR4.
A workaround first developed in the Pentium Pro, known as Physical Address Extension (PAE), allows certain 32-bit operating systems to access up to 36-bit memory addresses, even though individual programs are still limited to operating within 32 bits of address space. Provided there is enough memory installed, each program can have its own four ...
A system with a smaller page size uses more pages, requiring a page table that occupies more space. For example, if a 2 32 virtual address space is mapped to 4 KiB (2 12 bytes) pages, the number of virtual pages is 2 20 = (2 32 / 2 12). However, if the page size is increased to 32 KiB (2 15 bytes), only 2 17 pages are required. A multi-level ...
4-level paging of the 64-bit mode. In the 4-level paging scheme (previously known as IA-32e paging), the 64-bit virtual memory address is divided into five parts. The lowest 12 bits contain the offset within the 4 KiB memory page, and the following 36 bits are evenly divided between the four 9 bit descriptors, each linking to a 64-bit page table entry in a 512-entry page table for each of the ...