# # USB Core configuration # config USB_DEBUG bool "USB verbose debug messages" depends on USB help Say Y here if you want the USB core & hub drivers to produce a bunch of debug messages to the system log. Select this if you are having a problem with USB support and want to see more of what is going on. comment "Miscellaneous USB options" depends on USB config USB_DEVICEFS bool "USB device filesystem" depends on USB ---help--- 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, 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 usbfs file system to see the files, use mount -t usbfs none /proc/bus/usb For the format of the various /proc/bus/usb/ files, please read . Usbfs files can't handle Access Control Lists (ACL), which are the default way to grant access to USB devices for untrusted users of a desktop system. The usbfs functionality is replaced by real device-nodes managed by udev. These nodes live in /dev/bus/usb and are used by libusb. config USB_DEVICE_CLASS bool "USB device class-devices (DEPRECATED)" depends on USB default y ---help--- Userspace access to USB devices is granted by device-nodes exported directly from the usbdev in sysfs. Old versions of the driver core and udev needed additional class devices to export device nodes. These additional devices are difficult to handle in userspace, if information about USB interfaces must be available. One device contains the device node, the other device contains the interface data. Both devices are at the same level in sysfs (siblings) and one can't access the other. The device node created directly by the usb device is the parent device of the interface and therefore easily accessible from the interface event. This option provides backward compatibility for libusb device nodes (lsusb) when usbfs is not used, and the following udev rule doesn't exist: SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", \ NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0644" config USB_DYNAMIC_MINORS bool "Dynamic USB minor allocation (EXPERIMENTAL)" depends on USB && EXPERIMENTAL help If you say Y here, the USB subsystem will use dynamic minor allocation for any device that uses the USB major number. This means that you can have more than 16 of a single type of device (like USB printers). If you are unsure about this, say N here. config USB_SUSPEND bool "USB selective suspend/resume and wakeup (EXPERIMENTAL)" depends on USB && PM && EXPERIMENTAL help If you say Y here, you can use driver calls or the sysfs "power/state" file to suspend or resume individual USB peripherals. Also, USB "remote wakeup" signaling is supported, whereby some USB devices (like keyboards and network adapters) can wake up their parent hub. That wakeup cascades up the USB tree, and could wake the system from states like suspend-to-RAM. If you are unsure about this, say N here. config USB_PERSIST bool "USB device persistence during system suspend (DANGEROUS)" depends on USB && PM && EXPERIMENTAL default n help If you say Y here and enable the "power/persist" attribute for a USB device, the device's data structures will remain persistent across system suspend, even if the USB bus loses power. (This includes hibernation, also known as swsusp or suspend-to-disk.) The devices will reappear as if by magic when the system wakes up, with no need to unmount USB filesystems, rmmod host-controller drivers, or do anything else. WARNING: This option can be dangerous! If a USB device is replaced by another of the same type while the system is asleep, there's a good chance the kernel won't detect the change. Likewise if the media in a USB storage device is replaced. When this happens it's almost certain to cause data corruption and maybe even crash your system. If you are unsure, say N here. config USB_OTG bool depends on USB && EXPERIMENTAL select USB_SUSPEND default n config USB_OTG_WHITELIST bool "Rely on OTG Targeted Peripherals List" depends on USB_OTG default y help If you say Y here, the "otg_whitelist.h" file will be used as a product whitelist, so USB peripherals not listed there will be rejected during enumeration. This behavior is required by the USB OTG specification for all devices not on your product's "Targeted Peripherals List". Otherwise, peripherals not listed there will only generate a warning and enumeration will continue. That's more like what normal Linux-USB hosts do (other than the warning), and is convenient for many stages of product development. config USB_OTG_BLACKLIST_HUB bool "Disable external hubs" depends on USB_OTG help If you say Y here, then Linux will refuse to enumerate external hubs. OTG hosts are allowed to reduce hardware and software costs by not supporting external hubs.