Editing PCI configuration space (section)

== 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 [[API|APIs]] to allow access to device configuration space. When the operating system does not have access methods defined or APIs for memory mapped configuration space requests, the driver or diagnostic software has the burden to access the configuration space in a manner that is compatible with the operating system's underlying access rules. In all systems, device drivers are encouraged to use APIs provided by the operating system to access the configuration space of the device.