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One of the major improvements the PCI Local Bus had over other I/O architectures was its configuration mechanism. In addition to the normal memory-mapped and I/O port spaces, each device function on the bus has a configuration space, which is 256 bytes long, addressable by knowing the eight-bit PCI bus, five-bit device, and three-bit function numbers for the device (commonly referred to as the ...
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.
A third address space, called the PCI Configuration Space, which uses a fixed addressing scheme, allows software to determine the amount of memory and I/O address space needed by each device. Each device can request up to six areas of memory space or input/output (I/O) port space via its configuration space registers.
lspci is a command on Unix-like operating systems that prints ("lists") detailed information about all PCI buses and devices in the system. [1] It is based on a common portable library libpci which offers access to the PCI configuration space on a variety of operating systems.
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.
PCI configuration space; PCI Express; PCI eXtensions for Instrumentation; PCI hole; PCI-SIG; PCI-X; ... This page was last edited on 11 September 2020, at 02:34 (UTC).
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Configuration space may refer to: . Configuration space (physics) Configuration space (mathematics), the space of arrangements of points on a topological space PCI configuration space, the underlying way that the Conventional PCI, PCI-X and PCI Express perform auto configuration of the cards inserted into their bus