Re: Indexing problem with address number of a USB device

From: Naina Patrascu <patrascu.naina14_at_gmail.com>
Date: Tue, 1 Jun 2021 12:09:59 +0300
It worked!
Thank you!

You were right, we assigned the USB through bus and device address, but we
were comparing the port number in the enumeration process.

On Wed, May 12, 2021 at 10:24 PM Hans Petter Selasky <hps_at_selasky.org>
wrote:

> On 5/12/21 9:14 PM, John-Mark Gurney wrote:
> > Naina Patrascu wrote this message on Tue, May 11, 2021 at 18:47 +0300:
> >> We are working on the USB passthrough functionality for bhyve. We are
> >> currently focusing on the passthrough of a USB stick and a USB keyboard.
> >>
> >> We are facing an indexing problem when trying to assign a USB device to
> a
> >> virtual machine.
> >> For example, we have the USB keyboard at busnum=1 and devaddr=2 on the
> >> FreeBSD host virtual machine:
> >>
> >> # usbconfig -d ugen1.2
> >> ugen1.2: <Gaming KB Gaming KB> at usbus1, cfg=0 md=HOST spd=LOW
> (1.5Mbps)
> >> pwr=ON (100mA)
> >>
> >> We specify to "bhyve" command to pass through the device to a guest
> virtual
> >> machine: -s 30,xhci,1-2
> >>
> >> As part of the enumeration process, the host controller executes the
> >> internal scan to discover the physical devices and to compare them with
> the
> >> ones assigned with the bhyve command.
> >> But the USB device is discovered at bus 1 address 1, and we have to
> adjust
> >> accordingly when parsing the bus-port to match the port number:
> >>
> >> 04f3:152e 1-1 connecting.
> >> 04f3:152e 1-1 belong to this vm.
> >> 04F3:152E 1-1 is attached to virtual port 5.
> >>
> >> We hardcoded when parsing bus-port: port -= 1.
> >> When trying to pass through a USB stick, we have to increase the port
> >> number to match the one discovered in the internal scan:
> >>
> >> # usbconfig -d ugen3.2
> >> ugen3.2: <Kingston DataTraveler 3.0> at usbus3, cfg=0 md=HOST spd=HIGH
> >> (480Mbps) pwr=ON (300mA)
> >>
> >> 0951:1666 3-3 connecting.
> >> 0951:1666 3-3 belong to this vm.
> >> 0951:1666 3-3 is attached to virtual port 1.
> >>
> >> In our last investigation, we discovered that when increasing the
> number of
> >> USB devices on the FreeBSD host vm, the port indexes of the devices
> >> discovered by the internal scan, also varies.
> >>
> >> In function [1] we get the physical devices using libusb library and
> then
> >> we execute the internal scan using function [2]. We get the information
> >> about the physical device in function [3], also using libusb library.
> >>
> >> Can you help us understand where this problem could come from and how to
> >> debug it?
> >
> > Yes, the ugen named does not map to port naming.  I ran across this when
> > I did the work to make serial devices consistent based upon the port
> > number.  The review for that work is here:
> > https://reviews.freebsd.org/D21886#554613
> >
> > The device address is a different enumeration from the port address
> > information.  The script linked in the review creates a mapping from
> > the device name to the proper port number mapping.
> >
> > To see this, you can look at devinfo -v, and look at the port value
> > vs the devaddr (device address assigned at enumeration).
> >
> > Hope this helps.
> >
> >
>
> Hi,
>
> LibUSB in FreeBSD has a helper function to compute the full port topology:
>
>       libusb_get_port_numbers()
> and:
>
>       libusb20_dev_get_port_path()
>
> --HPS
>
Received on Tue Jun 01 2021 - 09:09:59 UTC

Original text of this message