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A peripheral using the PCI-SIG PCIe Address Translation Services (ATS) Page Request Interface (PRI) extension can detect and signal the need for memory manager services. For system architectures in which port I/O is a distinct address space from the memory address space, an IOMMU is not used when the CPU communicates with devices via I/O ports ...
The vast majority of Intel server chips of the Xeon E3, Xeon E5, and Xeon E7 product lines support VT-d. The first—and least powerful—Xeon to support VT-d was the E5502 launched Q1'09 with two cores at 1.86 GHz on a 45 nm process. [2]
The graphics address remapping table (GART), [1] also known as the graphics aperture remapping table, [2] or graphics translation table (GTT), [3] is an I/O memory management unit (IOMMU) used by Accelerated Graphics Port (AGP) and PCI Express (PCIe) graphics cards.
If the address field is non-zero, it is a disk address of the block, which has previously been rolled out — the block is fetched from disk, the pbit is set to one and the physical memory address updated to point to the block in memory. This makes descriptors equivalent to a page-table entry in an MMU system, but descriptors are free of a table.
Memory-mapped I/O is preferred in IA-32 and x86-64 based architectures because the instructions that perform port-based I/O are limited to one register: EAX, AX, and AL are the only registers that data can be moved into or out of, and either a byte-sized immediate value in the instruction or a value in register DX determines which port is the source or destination port of the transfer.
The display driver model from Windows 8.1 and Windows Phone have converged into a unified model for Windows 10. [43] A new memory model is implemented that gives each GPU a per-process virtual address space. Direct addressing of video memory is still supported by WDDMv2 for graphics hardware that requires it, but that is considered a legacy case.
HSA defines a special case of memory sharing, where the MMU of the CPU and the IOMMU of the GPU have an identical pageable virtual address space.. In computer hardware, shared memory refers to a (typically large) block of random access memory (RAM) that can be accessed by several different central processing units (CPUs) in a multiprocessor computer system.
Mac OS X Tiger through Mac OS X Snow Leopard support PAE and the NX bit on IA-32 processors; Snow Leopard was the last version to support IA-32 processors. On x86-64 processors, all versions of macOS use 4-level paging (IA-32e paging rather than PAE) to address memory above 4GB. Mac Pro and Xserve systems can use up to 64 GB of RAM. [23]