Mounting a USB stick with VirtualBox

I used VirtualBox to create a bootable USB key with FreeBSD using VirtualBox on my Mac. Here are a few issues I ran into.

USB2 is not supported by VirtualBox

VirtualBox does not support USB2 by default. If you try to mount a USB device, you will get a warning that it requires 'Oracle VM VirtualBox Extension Pack'. Download from the VirtualBox website and install extension pack (which contains binary USB 2 driver)

Determine the mount location of the disk

The mount location of the USB disk is determined by your operating system and presently available hardware. The names typically take these forms:

• /dev/da0 on FreeBSD
• /dev/disk2 on Mac OS X
• /dev/sda1 on Linux

If the USB key is already mounted, these tools list the mounted disks:

• mount on Linux and FreeBSD
• diskutil list on Mac OS X

Mac does not fully unmount USB stick

Problem: Ejecting a disk in the Finder only ejects the partition, but does not unmount the whole disk.

Solution: determine the disk, and unmount using diskutil:

diskutil list
diskutil unmountDisk /dev/disk2

No USB devices found

Deattach USB disk from host computer, and attach to to Virtual Box.

Problem

Installer shows up, but I can't select a USB disk. Even after rescanning, and checking the fixit menu, it gaves an error "No USB devices found".

Solution

I installed FreeBSD on virtual disk, instead of USB disk. Succeeded.

USB_ERR_TIMEOUT

Booted FreeBSD in VirtualBox, and attached USB disk. Error:

uhub_reattach_port: port 1 reset failed, error=USB_ERR_TIMEOUT
uhub_reattach_port: device problem (USB_ERR_TIMEOUT), disabling port 1

Seems a bug in VirtualBox. See issue #8182

In VirtualBox settings (under ports > USB) Disable USB 2.0 (EHCI) Controller.

Reboot the Virtual box.

Now the USB key works fine in FreeBSD, and is made available at /dev/da0..