About USB in the Solaris Environment

The following sections describe specific information you should know about USB in the Solaris environment.

USB Keyboards and Mouse Devices

Keep only one USB keyboard and mouse on the system at all times because multiple USB keyboards and mouse devices are not supported in the Solaris environment. See the following items for specific details.

• A keyboard and mouse that are connected anywhere on the bus are configured as console keyboard and mouse. Booting the system is slower if the keyboard and mouse are not on the root hub.

• You can move a console keyboard and mouse to another hub at any time after a system reboot. You cannot move the console keyboard and mouse during a reboot or at the ok prompt. After you plug in the keyboard and mouse, they are fully functional again.

• SPARC only – The power key on a USB keyboard behaves differently than the one on the Sun Type–5 keyboard. On a USB keyboard, you can suspend or shut down the system by using the SUSPEND/SHUTDOWN key, but you cannot power-on the system.

• The left side of the keypad functionality is unavailable on non-Sun USB keyboards.

• Multiple keyboards are not supported:

  • The keyboards enumerate and are usable, but they are not plumbed as console keyboards.

  • The first keyboard that is probed at boot time becomes the console keyboard. The result of this probing might cause confusion if multiple keyboards are plugged in at boot time.

  • If you unplug the console keyboard, the next available USB keyboard doesn't become the console keyboard. The next hot-plugged keyboard becomes the console keyboard.

• Multiple mouse devices are not supported:

  • The mouse devices enumerate and are usable, but they are not plumbed as console mouse devices.

  • The first mouse that is probed at boot time becomes the console mouse. The result of this probing might cause confusion if you have multiple mouse devices plugged in at boot time.

  • If you unplug the console mouse, the next available USB mouse doesn't become the console mouse. The next hot-plugged mouse becomes the console mouse.

• If you have a non-Sun (third-party) composite keyboard with a PS/2 mouse, and it is the first one to be probed, it becomes the console keyboard/mouse even if the PS/2 mouse is not plugged in. This means another USB mouse plugged into the system cannot work because it is not configured as the console mouse.

• Only two-button and three-button mouse devices are supported. A wheel-on-wheel mouse acts like a plain-button mouse. A mouse with more than three buttons functions like a three–button mouse.

USB Host Controller and Root Hub

A USB hub is responsible for:

• Monitoring the insertion or removal of a device on its ports

• Power-managing individual devices on its ports

• Controlling power to its ports

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

• Directing the USB bus. Individual devices cannot arbitrate for the bus.

• Polling the devices by using a polling interval determined by the device. The device is assumed to have sufficient buffering to account for the time between the polls.

• Sending data between the USB host controller and its attached devices. Peer-to-peer communication is not supported.

USB Hub Devices

• Do not cascade hubs beyond four levels on either SPARC or IA systems. On SPARC systems, the Open Boot PROM (OBP) cannot reliably probe beyond four levels of devices.

• Do not cascade bus-powered hubs. This means you cannot plug a bus-powered hub into another bus-powered hub. A bus-powered hub does not have its own power supply. A USB diskette device derives all its power from the bus and might not work on a bus-powered hub.

USB Storage Devices

Removable mass storage devices such as USB Zip, Jaz, Clik!, SmartMedia, CompactFlash, and ORB are supported, starting with the Solaris 8 10/00 release. See scsa2usb(7D) for a complete list of devices that are supported in the Solaris environment.

These devices can be managed with or without volume management. See vold(1M) for information on managing devices with volume management.

SPARC Only: USB Power Management

If the system has enabled power management, the USB framework makes a best effort to power-manage all devices. Power-managing a USB device means the hub driver suspends the port to which the device is connected. The device might or might not support remote wakeup. If the device supports remote wakeup, it wakes up the hub it is connected to, depending on the event, such as moving the mouse. The host system could also wake the device if an application sends an I/O to it.

All HID (keyboard, mouse, and so forth), hub, and storage devices are power-managed by default if they support the remote wakeup capability. A USB printer is power-managed only between two print jobs.

When you power-manage to reduce power consumption, USB leaf devices are powered down first, and after some delay, the parent hub is powered down. When all devices that are connected to this 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.

Hot-Plugging USB Devices

When you plug in a USB device, the device is immediately seen in the system's device hierarchy, as displayed in the prtconf(1M) command output. When you remove a USB device, the device is removed from the system's device hierarchy, unless the device is in use.

If the USB device is in use when it is removed, the hot-plug behavior is a little different. If a device is in use when it is unplugged, the device node remains, but the driver controlling this device stops all activity on the device. Any new I/O activity issued to this device is returned with an error.

In this situation, the system prompts you to plug in the original device. To recover from accidentally removing a busy USB device, do the following:

1. Plug the original device into the same port.

2. Stop the application that is using the device.

3. Remove the device.

The USB port remains unusable until the original device has been plugged in again. If the device is no longer available, the port remains unusable until the next reboot.

Data integrity might be impaired if you remove an active or open device. Always close the device before removing, except the console keyboard and mouse, which can be moved while active.

USB Cables

Never use USB cable extenders that are available in the market. Always use a hub with longer cables to connect devices. Always use fully rated (12 Mbit/sec) 20/28 AWG cables for connecting USB devices.