On Wed Jun 15 11, Hans Petter Selasky wrote:
> On Wednesday 15 June 2011 11:33:14 Alexander Best wrote:
> > On Tue Jun 14 11, Hans Petter Selasky wrote:
> > > On Tuesday 14 June 2011 14:52:08 Alexander Motin wrote:
> > > > Hans Petter Selasky wrote:
> > > Done:
> > >
> > > http://svn.freebsd.org/changeset/base/223098
> > btw., if i might ask a technical and probably naive question:
> > does USB 3.0 feature *full* backward compatibility? that is supporting usb
> > 1.x and usb 2.0 devices without the need for enabling those legacy
> > controllers?
> Yes, XHCI is a replacement for EHCI and OHCI and UHCI. It speaks multiple
thanks a lot for clearing things up. :)
> > so will xhci give me all the backward compatibility or do i have to also
> > enable a combination of ohci/uhci/ehci? with usb 2.0 there was no usb 1.x
> > support unless ohci/uhci was also enabled.
> > i read that the xhci controllers don't depend on CPU and I/O availability
> > as much as the old controllers. doing CPU intensive tasks shouldn't have
> > such a massive effect on USB transfer times, compared to usb 1.x and 2.0.
> > that's why i'd like to completely get rid of the need for ohci/uhci/ehci
> > in my kernel config.
> Due to certain commercial OS'es which haven't got XHCI support, hardware
> manufacturers have come up with creative solutions which involves custom bits
> to switch ports to and from XHCI/EHCI.
> > i'd really like to see some transfer time statistics with CPU being close
> > to 100% idle and with CPU being hammered close to 100% with usb 3.0. i
> > think i did such a test a while ago for usb 2.0 and transfer rates dropped
> > quite significantly.
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