The eXtensible Host Controller Interface (xHCI) specification describes the register-level host controller interface for universal serial bus revision 2.0 (USB2) and above. The specification includes a description of the hardware/software interface between system software and the host controller hardware. This specification is intended for hardware component designers, system builders, and device driver (software) developers. The reader is expected to be familiar with the current universal serial bus specification revisions. In spite of due diligence, there may exist conflicts between this specification and the USB specification. The USB specifications take precedence on all issues of conflict.
Scope of Document
The specification is primarily targeted to host controller developers and system OEMs, but provides valuable information for platform operating system and BIOS device driver developers, adapter IHVs/ISVs, and platform/adapter controller vendors. This specification can be used for developing new products and associated software.