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eXtensible Host Controller Interface (xHCI) is a computer interface specification that defines a register-level description of a Host Controller for Universal Serial bus (USB), which is capable of interfacing with USB 1.x, 2.0, and 3.x compatible devices. The specification is also referred to as the USB 3.0 Host Controller specification. == Architectural goals == The xHCI is a radical break from the previous generations of USB host controller interface architectures (i.e. the Open Host Controller Interface (OHCI), the Universal Host Controller Interface (UHCI), and the Enhanced Host Controller Interface (EHCI)) on many counts. Following are the key goals of the xHCI architecture: * Efficient operation – idle power and performance better than legacy USB host controller architectures. * A device level programming model that is fully consistent with the existing USB software model * Decouple the host controller interface presented to software from the underlying USB protocols * Minimize host memory accesses, fully eliminating them when USB devices are idle * Eliminate register writes and minimize register reads for normal data transfers * Eliminate the “Companion Controller” model * Enable hardware “fail-over” modes in system resource constrained situations so devices are still accessible, but perhaps at less optimal power/performance point * Provide the ability for different markets to differentiate hardware capabilities, e.g. target host controller power, performance and cost trade-offs for specific markets * Define an extensible architecture that provides an easy path for new USB specifications and technologies, such as higher bandwidth interfaces, optical transmission medium, etc., without requiring the definition of yet another USB host controller interface 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Extensible Host Controller Interface」の詳細全文を読む スポンサード リンク
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