subsystem which offers higher speeds and more features than the traditional PC serial port. The bus supplies power to peripherals and allows for hot swapping. Up to 127 USB peripherals can be connected to a single USB port in a tree structure. The USB port is the root of the tree, the peripherals are the leaves and the inner nodes are special USB devices called hubs. Many newer PC's have USB ports and newer peripherals such as scanners, keyboards, mice, modems, and printers support the USB protocol and can be connected to the PC via those ports.
Say Y here if your computer has a USB port and you want to use USB devices. You then need to say Y to at least one of "UHCI support" or "OHCI support" below (the type of interface that the USB hardware in your computer provides to the operating system) and then choose from among the drivers for USB peripherals. You may want to check out the information provided in Documentation/usb/ and especially the links given in Documentation/usb/usb-help.txt.
This code is also available as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called usbcore.o. If you want to compile it as a module, say M here and read Documentation/modules.txt.
If you say Y here (and to "/proc file system support" in the "File systems section, above), you will get a file /proc/bus/usb/devices which lists the devices currently connected to your USB bus or busses, a file /proc/bus/usb/drivers which lists the USB kernel client drivers currently loaded, and for every connected device a file named "/proc/bus/usb/xxx/yyy", where xxx is the bus number and yyy the device number; the latter files can be used by user space programs to talk directly to the device. These files are "virtual", meaning they are generated on the fly and not stored on the hard drive.
You may need to mount the usbdevfs file system to see the files, use mount -t usbdevfs none /proc/bus/usb
For the format of the various /proc/bus/usb/ files, please read Documentation/usb/proc_usb_info.txt.
Please note that this code is completely unrelated to devfs, the "/dev file system support".
Most users want to say Y here.
The Universal Host Controller Interface is a standard by Intel for accessing the USB hardware in the PC (which is also called the USB host controller). If your USB host controller conforms to this standard, you may want to say Y, but see below. All recent boards with Intel PCI chipsets (like intel 430TX, 440FX, 440LX, 440BX, i810, i820) conform to this standard. Also all VIA PCI chipsets (like VIA VP2, VP3, MVP3, Apollo Pro, Apollo Pro II or Apollo Pro 133). If unsure, say Y.
Currently there exist two drivers for UHCI host controllers: this so-called JE driver, and the one you get from "UHCI support", above. You need only one.
This code is also available as a module ( = code which can be inserted in and removed from the running kernel whenever you want). x The module will be called uhci.o. If you want to compile it as a module, say M here and read Documentation/modules.txt.