How to mount a VirtualBox vdi image as a drive in linux
#install tools
$ sudo apt-get install qemu-kvm
#load module
$ sudo modprobe nbd
#create loopback dev for the image
$ sudo qemu-nbd -c /dev/nbd0 <image>.vdi
#mount the partitions, that are exposed as /dev/nbd0pXXX
$ sudo mount -o noatime,noexec /dev/nbd0p1 /tmp/vdi/
#in the end unmount && shutdown the ndb
$ sudo umount /tmp/vdi/
$ sudo qemu-nbd -d /dev/nbd0