System Administration Guide: Devices and File Systems

About USB in the Solaris OS

This section describes information you should know about USB in the Solaris OS.

USB 2.0 Features

The following USB 2.0 features are included:

For a description of USB devices and terminology, see Overview of USB Devices.

USB 2.0 Device Features and Compatibility Issues

USB 2.0 devices are defined as high-speed devices that follow the USB 2.0 specification. You can refer to the USB 2.0 specification at

To identify the speed of your USB device in the Solaris 10 releases, check the /var/adm/messages file for messages similar to the following:

Dec 13 17:05:57 mysystem usba: [ID 912658] USB 2.0 device
(usb50d,249) operating at hi speed (USB 2.x) on USB 2.0 external hub:
storage@4, scsa2usb0 at bus address 4

Here are some of the USB devices that are supported in this Solaris release:

For a full listing of USB devices that have been verified on the Solaris release, go to:

Additional storage devices might work by modifying the scsa2usb.conf file. For more information, see scsa2usb(7D).

Solaris USB 2.0 device support includes the following features:

For more information on USB 2.0 device support, see ehci(7D) and usba(7D).

Bus-Powered Devices

Bus-powered hubs use power from the USB bus to which they are connected, to power devices connected to them. Special care must be taken to not overload these hubs, because the power these hubs offer to their downstream devices is limited.

Starting in the Solaris Express release, power budgeting is implemented for USB devices. This feature has the following limitations:

USB Keyboards and Mouse Devices

Keep the following issues in mind when using USB keyboards and mouse devices:

USB Wheel Mouse Support

Starting in the Solaris 9 9/04 release, the following wheel mouse features are supported:

USB Host Controller and Hubs

A USB hub is responsible for the following:

The USB host controller has an embedded hub called the root hub. The ports that are visible at the system's back panel are the ports of the root hub. The USB host controller is responsible for the following:

USB Hub Devices

SPARC: USB Power Management

Suspending and resuming USB devices is fully supported on SPARC systems. However, do not suspend a device that is busy and never remove a device when the system is powered off under a suspend shutdown.

The USB framework makes a best effort to power manage all devices on SPARC based systems with power management enabled. Power managing a USB device means that the hub driver suspends the port to which the device is connected. Devices that support remote wake up can notify the system to wake up everything in the device's path so that the device can be used. The host system could also wake up the device if an application sends an I/O to the device.

All HID devices (keyboard, mouse, hub, and storage devices), hub devices, and storage devices are power managed by default if they support remote wake-up capability. A USB printer is power managed only between two print jobs. Devices that are managed by the generic USB driver (UGEN) are power managed only when they are closed.

When power management is running to reduce power consumption, USB leaf devices are powered down first. After all devices that are connected to a hub's ports are powered down, the hub is powered down after some delay. To achieve the most efficient power management, do not cascade many hubs.

For information about using the SUSPEND/SHUTDOWN key on SPARC systems, see USB Keyboards and Mouse Devices.

Guidelines for USB Cables

Keep the following guidelines in mind when connecting USB cables:

For more information, go to: