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What is USB 3.0?

USB 3.0 is a new Universal Serial Bus specification that was released in November 2008. It promises wire speeds of 5Gbps, bi-directional communication, and better power management.

What is xHCI?

The eXtensible Host Controller Interface (xHCI) is the hardware on your PC that talks to USB 3.0 devices and legacy USB devices. The xHCI specification details can be found on Intel's website.

Wasn't USB 2.0 good enough? Why is USB 3.0 cool?

USB 3.0 is expected to be 10 times faster than USB 2.0. It's also more power efficient, which translates into longer laptop battery life. Since USB 3.0 packets are routed instead of broadcast, idle links can be automatically put into low power states without the help of an operating system. USB 3.0 also adds the concept of endpoint "streams", which are used to submit multiple SCSI commands and get better performance out of USB attached SCSI hard drives and flash drives.

What about all my old USB devices?

Older USB devices will still work when you plug them into a USB 3.0 port on an xHCI host controller. They will still operate at their original speeds.

Can I plug a USB 3.0 device into my old computer?

If you plug a USB 3.0 device into an EHCI host controller, it will work at USB 2.0 speeds. To get 5Gbps wire speed, you need an xHCI host controller.

USB 3.0 sounds pretty cool. When will Linux support it?

The Linux xHCI driver has been merged into 2.6.31. The git development tree for the driver can be found on kernel.org

Is there any mailing list for xhci driver related discussions?

You can subscribe to the linux-usb mailing list at http://www.linux-usb.org/mailing.html I'll also post updates on my blog.

I found a bug in the xHCI driver. What should I do?

Enable xHCI debugging in your kernel (CONFIG_USB_XHCI_HCD_DEBUGGING) and send your dmesg output to sarah.a.sharp@linux.intel.com. Please CC the Linux USB mailing list linux-usb@vger.kernel.org.

You didn't answer my question; where can I find more info?

See a longer blog post for more information.

First and foremost, I am a geek. When I get into a hobby, I focus on it completely; I learn all the rules, nuances, and vocabulary so that I can have an in-depth conversation with an expert. I love technology, mostly for the ways that it eliminates repetitive tasks and allows people to connect. I love open source because it creates an open community that helps the software (and hardware) evolve into something useful and usable.

Linux

I've been running Linux for about five years, and I've been developing on Linux for the past two years. I currently work in Intel's Open Source Technology Center. I currently work on the Linux USB subsystem. The comments and content on this blog are mine, and do not reflect my employer's opinions.

Amateur Rocketry

My most "explosive" hobby is amateur rockets. I'm involved with the Portland State Aerospace Society, who designs, builds, and launches open source rockets. I got involved in USB because the sensor nodes (GPS, IMU, temperature, pressure, etc.) are going to be USB devices that talk to our Linux flight computer. If you want to know more, you should checkout the five-minute intro talk I gave at Ignite Portland 2:

Of course, my life isn't all about technology!

Personal

I'm happily married to Jamey Sharp, who is also a fellow geek.

Gardening

I had a garden in a local community garden for two years, and this year I decided to make a garden at the house I'm renting. Being the geek that I am, I decided to do the whole thing myself, so that I could learn about landscaping. It's been a slow, but interesting process. Pictures will be posted as the work progresses.

Bicycling

When I started working at Intel, I faced a 20 mile commute. I could have picked the easy route and bought myself a car. However, I'm environmentalist at heart, so I decided to use mass transit. It was a 10-minute walk to get to the MAX station, a 30-minute ride to Hillsboro, and a 5-minute shuttle ride to work. After a month, I got tried of being tied to the Intel shuttle schedule, and I started biking on both ends of my commute.

Since that time, I've become a big bicycle geek. My family often worries about my safety, but the only accident I've gotten into was my own fault. Portland is very bike friendly, and I love to bike to local cafes and spend the day hacking. Portland has a very active bike community, and I'm slowly going on more group rides. Some day I'd like to do a bicycle tour of the Columbia River Gorge and the Oregon Coast.

Travel

I love to travel. I love to see new sights and talk to the locals about their culture. My mom instilled the travel bug in me; I went to Europe seven times before I graduated high school. Most American kids don't get that kind of perspective, and I'm very grateful for my experiences.

My mom was into whirlwind tours that included all the sights; my dad was into going to Pubs and talking with the locals. I like my dad's approach better. I believe that you can't really get the flavor of a town until you spend at least three or four days in it, and that you can't judge a country (or state) by one town. Whirlwind tours are not for me.

I love to go off the beaten path, away from the tourist attractions. I will always prefer nature to a mall.

Places I've been:

• Canada: Victoria, BC; the Canadian Gulf Islands; Quebec City
• The Caribbean
• England: London, Brighton, Bath, Stone Henge.
• France: Paris, Nice, Cannes, Amboise, Bois, and the French Alps.
• Switzerland
• United States:
  • California: LA, San Francisco
  • Hawaii: Kauai and Hawaii
  • Illinois: Joliet and Kankakee
  • Idaho: somewhere with a giant lake?
  • Nevada: the Blackrock Desert
  • Oregon: the Columbia River Gorge, the Oregon coast, Eastern Oregon around Bend. My childhood stomping grounds included Rainier, Goble, and Prescott.
  • South Dakota
  • Washington: Seattle, the San Juan Islands
• Japan: Tokyo, Nikko, Sendai, Matsushima, Tono

Places I want to travel to:

• Japan
• Austria
• Scotland
• New Zealand
• Belgium
• the Netherlands
• various places in the United States
  • Alaska
  • Maine or New Hampshire to see the fall colors
  • Yosemite National Park

Miscellaneous

I'm a tea snob. I have been ever since I visited London, England.

In spring 2007, I took a scuba class with my fiancé, and we got our NAUI certification. In June 2007, we went on our honeymoon to Hawaii. My husband and I snorkled the beaches and went on two scuba diving tours. I got to see turtles, manna rays, and all sorts of colorful fishes. I haven't been diving since, mostly because I hate the cold water in the Northwest. I would like to give it another try some day soon.

I'm a big bookworm, although my other hobbies have been taking more of my time lately. My current bent is towards fantasy and science fiction books. Favorite authors include:

• Laurie R. King
• Diane Duane
• Terry Pratchett
• Diana Wynn Jones

I may occasionally post a book review if I get ambitious.

I'm terrible at spelling. In Kindergarten, I was taught to spell things the way they sound. That was an utter disaster. Vim automatic spell checking is my crutch, and I often defer to Google when that fails me. Please excuse any spelling errors in my entries.