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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 ...
This is similar to an I/O read, but reads from PCI configuration space. A device must respond only if the low 11 bits of the address specify a function and register that it implements, and if the special IDSEL signal is asserted. It must ignore the high 21 bits. Burst reads (using linear incrementing) are permitted in PCI configuration space.
PCI Express devices communicate via a logical connection called an interconnect[ 10 ] or link. A link is a point-to-point communication channel between two PCI Express ports allowing both of them to send and receive ordinary PCI requests (configuration, I/O or memory read/write) and interrupts (INTx, MSI or MSI-X).
The PCI-X standard was developed jointly by IBM, HP, and Compaq and submitted for approval in 1998. It was an effort to codify proprietary server extensions to the PCI local bus to address several shortcomings in PCI, and increase performance of high bandwidth devices, such as Gigabit Ethernet, Fibre Channel, and Ultra3 SCSI cards, and allow processors to be interconnected in clusters.
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.
Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, [ 1 ][ 2 ][ 3 ] which became ubiquitous in the IBM PC compatible industry within three years. [ 4 ] The term can now refer to the computer display standard, the 15-pin D-subminiature ...
This allows it to scan the PCI configuration space to find the correct device and BARs it needs to use. To prevent this scan, and in case of two identical cards in the system, the BIOS passes the PFA (bus/device/function) to the initialization routine in AX, and the card select number (CSN) for ISA option ROMs is passed in BX.
The virtual or physical functions available to the hypervisor or guest operating system depend on the PCIe device. [3] The SR-IOV allows different virtual machines (VMs) in a virtual environment to share a single PCI Express hardware interface. In contrast, MR-IOV allows I/O PCI Express to share resources among different VMs on different ...