Bug 1271408 - RFE: qemu: support configuring # of ports for qemu usb3 controller
RFE: qemu: support configuring # of ports for qemu usb3 controller
Product: Virtualization Tools
Classification: Community
Component: libvirt (Show other bugs)
Unspecified Unspecified
unspecified Severity unspecified
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Assigned To: Libvirt Maintainers
Depends On:
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Reported: 2015-10-13 18:15 EDT by Cole Robinson
Modified: 2016-05-04 05:46 EDT (History)
4 users (show)

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Doc Type: Bug Fix
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Last Closed: 2016-05-03 09:03:51 EDT
Type: Bug
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Description Cole Robinson 2015-10-13 18:15:46 EDT
According to Gerd here:


qemu's xhci controller has a configurable number of ports. libvirt should support that, since the default is only 4.
Comment 1 Cole Robinson 2015-10-13 18:23:54 EDT
Gerd, is this all that's required to give the xhci controller ex. 8 ports?

  -device nec-usb-xhci,p2=8,p3=8

Also, any opinions on if we should expose p2 vs p3 or just a single 'ports' knob? I don't know what the usecase for configuring only one or the other is...
Comment 2 Gerd Hoffmann 2015-10-14 01:48:22 EDT
p2 is the number of usb2 ports, p3 is the number of usb4 ports.  Ports do overlap.  So for example p2=8,p2=4 gives you a xhci controller where ports 1-4 can do both usb2 and usb3, whereas ports 5-8 are usb2 only.

That is mostly useful for debugging/testing purposes, for example forcing devices into usb2 mode on xhci to see whenever this works correctly.

I'd suggest to expose this as a single ports= property in libvirt.
Comment 3 Cole Robinson 2016-04-27 14:30:38 EDT
Patches posted upstream: http://www.redhat.com/archives/libvir-list/2016-April/msg01829.html
Comment 4 Cole Robinson 2016-05-03 09:03:51 EDT
Upstream now:

commit 600977e293ee97fc53a7ef17fb89cb310560e7ab
Author: Cole Robinson <crobinso@redhat.com>
Date:   Sat Apr 23 19:52:56 2016 -0400

    qemu: support configuring usb3 controller port count
    This adds a ports= attribute to usb controller XML, like
      <controller type='usb' model='nec-xhci' ports='8'/>
    This maps to:
      qemu -device nec-usb-xhci,p2=8,p3=8
    Meaning, 8 ports that support both usb2 and usb3 devices. Gerd
    suggested to just expose them as one knob.

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