USB3 (wasMoving an HD from one comp to another)

[Tyler Aviss]

That's what I was afraid of. Ah well, I guess I'll just have to hold
out for USB3 boards and then get a USB3 drive-enclosure. Until then
there's always eSATA as well, which is becoming fairly popular it
seems (probably due the USB2-IO=suck issues mentioned)

Thanks for the info though, it's very informative!

On Fri, Nov 26, 2010 at 10:56 AM, Lennart Sorensen
<lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org> wrote:
> On Fri, Nov 26, 2010 at 10:36:49AM -0800, Tyler Aviss wrote:
>> So if you connect a USB2 device to a computer's USB3 bus, does it work
>> happily without crapping out the CPU, or only enable DMA/interrupt for
>> USB3 enabled devices?
>
> No.  A USB3 port is really two ports in one.  It is a USB2 port with
> all the regular pins and an EHCI+OHCI/UHCI controller, and then it is
> an XHCI controller as well using seperate data lines for USB3 devices.
> Devices start out talking to the USB2 part of the port, and if the device
> and the port and any hubs along the way are all able to do USB3, then
> they enable the USB3 part of the link for data transfers.  Some control
> messages will still use the USB2 part of the link at times apparently.
>
> A USB3 port will not make any change in behaviour to USB1 or 2 devices.
> The USB1/2 protocol has no concept of interrupts or DMA.  USB3 has a
> lot more in the protocol, but only USB3 devices and ports support the
> new features.
>
>> I haven't bought any USB3-enabled boards yet. What's the state of
>> linux-friendliness of the controllers. I know i've had a lot of USB2
>> devices that would drop-off on various boards in 'nix but not in
>> windows for some reason...
>
> Linux has XHCI controller support for a while now.  Probably had it a
> while before windows did.  That was the case with USB2's EHCI in the
> past as well.  Linux had it first.
>
> Some USB2 controllers were badly made, and there were a few kernel bugs
> some years ago too that affected some implementations (SiS chip sets
> were especially effected)
>
> --
> Len Sorensen
> --
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-- 
Tyler Aviss
Systems Support
LPIC/LPIC-2/DCTS/CLA

“It can takes months to gain a customer, but only seconds to lose one"
--
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TLUG requests: Linux topics, No HTML, wrap text below 80 columns
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