VirtualBox is listed in the README file under virtual machine images on the latest release: https://www.freebsd.org/where.html. However, I was unable to get FreeBSD to boot with any of the .qcow files listed. VirtualBox doesn't have an option to boot from the file format. I was able to get VirtualBox to work with the "disc1.iso" format listed under the main section for installer images. If the release page could indicate that this is the case, it could clear up some confusion. Also (very minor note, probably not important) the README file is a bit hard to locate due to being the same style/font/color as the other links. Could be helpful to separate it for visibility.
I just verified it. Downloaded the qcow2 10.3. image, extracted it from the xz and created a new VirtualBox VM using that qcow2 file as the underlying disk. After starting the VM I get: FATAL: Could not read from the boot medium! System halted. A quick search on the web revealed this: https://forums.virtualbox.org/viewtopic.php?f=1&t=75859 The issue seems to be with VirtualBox, not FreeBSD. To convert your qcow2 image to VDI, which you can then import as a new VM in VirtualBox, open a console and enter this: VBoxManage convertfromraw --format vdi /path/to/FreeBSD-10.3-RELEASE-amd64.qcow2 /output/path/FreeBSD-10.3-RELEASE-amd64.vdi We should think about providing VDI (or any other format) files instead of QCOW until VirtualBox fully supports running that format.
batch change: For bugs that match the following - Status Is In progress AND - Untouched since 2018-01-01. AND - Affects Base System OR Documentation DO: Reset to open status. Note: I did a quick pass but if you are getting this email it might be worthwhile to double check to see if this bug ought to be closed.
Now, the README[1] of the VM clarifies that the .qcow2 is for QEMU and KVM. [1] https://download.freebsd.org/ftp/releases/VM-IMAGES/README.txt