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Overview. PCI devices have a set of registers referred to as configuration space and PCI Express introduces extended configuration space for devices. Configuration space registers are mapped to memory locations. Device drivers and diagnostic software must have access to the configuration space, and operating systems typically use APIs to allow ...
Each device can request up to six areas of memory space or input/output (I/O) port space via its configuration space registers. In a typical system, the firmware (or operating system ) queries all PCI buses at startup time (via PCI Configuration Space ) to find out what devices are present and what system resources (memory space, I/O space ...
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.
An option ROM for the PC platform (i.e. the IBM PC and derived successor computer systems) is a piece of firmware that resides in ROM on an expansion card (or stored along with the main system BIOS), which gets executed to initialize the device and (optionally) add support for the device to the BIOS. In its usual use, it is essentially a driver ...
Message Signaled Interrupts (MSI) are a method of signaling interrupts, using special in-band messages to replace traditional out-of-band signals on dedicated interrupt lines. While message signaled interrupts are more complex to implement in a device, they have some significant advantages over pin-based out-of-band interrupt signalling, such ...
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 ...
A PCI-104 single-board computer. PC/104 (or PC104) is a family of embedded computer standards which define both form factors and computer buses by the PC/104 Consortium.Its name derives from the 104 pins on the interboard connector in the original PC/104 specification [1] [2] and has been retained in subsequent revisions, despite changes to connectors.
CXL.io – based on PCIe 5.0 (and PCIe 6.0 after CXL 3.0) with a few enhancements, it provides configuration, link initialization and management, device discovery and enumeration, interrupts, DMA, and register I/O access using non-coherent loads/stores. [38]