How to: USB Passthrough
Firstly, QEMU must be started as root. 

It is also potentially possible to accomplish USB passthrough by changing the permissions of the device in the container.
See [here](https://www.linuxquestions.org/questions/slackware-14/qemu-usb-permissions-744557/#post3628691).

For example, create a new Dockerfile with the following

```bash
FROM sickcodes/docker-osx
USER arch
RUN sed -i -e s/exec\ qemu/exec\ sudo\ qemu/ ./Launch.sh
COPY --chown=arch ./new_image.img /home/arch/OSX-KVM/mac_hdd_ng.img
```

Where `new_image.img` is the qcow2 image you extracted. Then rebuild with `docker build .`

Next we need to find out the bus and port numbers of the USB device we want to pass through to the VM:

```bash
lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 5000M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
    |__ Port 2: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 12M
    |__ Port 2: Dev 5, If 1, Class=Chip/SmartCard, Driver=, 12M
    |__ Port 3: Dev 2, If 0, Class=Wireless, Driver=, 12M
    |__ Port 3: Dev 2, If 1, Class=Wireless, Driver=, 12M
    |__ Port 5: Dev 3, If 0, Class=Video, Driver=uvcvideo, 480M
    |__ Port 5: Dev 3, If 1, Class=Video, Driver=uvcvideo, 480M
```

In this example, we want to pass through a smartcard device. The device we want is on bus 1 and port 2.

There may also be differences if your device is usb 2.0 (ehci) vs usb 3.0 (xhci).
See [here](https://unix.stackexchange.com/a/452946/101044) for more details.

```bash