I'm launching a VM using qemu-system-x86_64. I know two ways to pass through a USB device.

Say for example, I had a mouse that showed up in lsusb like

Bus 003 Device 011: ID 6ade:9582 Amazing Mouse Maker

I could pass it through using

-device usb-host,vendorid=0x6ade,productid=0x9582


-device usb-host,hostbus=3,hostaddr=11

Neither of these I really like. If I grab it by Vendor/Product ID then I will never be able to reclaim that mouse until the VM is turned off.

If I grab it by BUS and Device number, then I will have to tell Qemu to reacquire it if I unplug it.

Is it possible for me to send it by Port (the actual physical slot)? Say it's plugged in to Bus 3 Port 2. Can I pass it by that?


For some reason this is not documented on the Qemu 2.12.50 User Doc and I had to learn what I learned from this guy

They mention

-device usb-host,hostbus=bus,hostaddr=addr
Pass through the host device identified by bus and addr 

-device usb-host,vendorid=vendor,productid=product
Pass through the host device identified by vendor and product ID 

But they don't mention that you can do

-device usb-host,hostbus=bus,hostport=port

For example...

If I run lsusb -t and get

/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/14p, 480M
|__ Port 10: Dev 8, If 0, Class=Human Interface Device, Driver=usbhid, 12M
|__ Port 11: Dev 6, If 0, Class=Human Interface Device, Driver=usbhid, 12M

I could decide to pass these by

-device usb-host,hostbus=3,hostport=10 \
-device usb-host,hostbus=3,hostport=11 \

And those correspond to the physical slots.

However the bus and port will differ for a USB 3.0 slot depending on if a USB 2.0 device or USB 3.0 device is plugged into it, but the port for each device will remain consistent.

Such variance does not exist for USB 2.0 slots.

/* update: USB Hubs */

Use dots to separate the ports. So if you had ...

/:  Bus 03
|__ Port 2: some stuff
    |__ Port 1: some stuff

You would use -device usb-host,hostbus=3,hostport=2.1

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