Virtualbox is hypervisor for newbies training. VirtualBox have simple graphical user interface and simplicity. VirtualBox can run on multiple operating systems like Apple MacOS, Microsoft Windows and Linux.

ULFS provide VirtualBox OVA-packages especialy for Virtualbox users. They can be used to deploy demo virtual machines of desktop and local repository. Desktop OVA-package contain VirtualBox additions.

Regular images don't contain VirtualBox guest additions and not ready to run.

To prepare disk images to run in Virtual Box it should be converted from raw or qcow format to vdi format. You can use qemu-img tool to conver image to vdi-format:

qemu-img convert -O vdi hdd.img hdd.vdi

To install virtualbox guest additions you have to do:

Warning: VirtialBox is not suport VirtIO disk drive therefore grub and fstab should be configured to use sda1 as root partition not vda1.

There are bug with kernel which affect additional resolution modes support by Xorg. To fix this bug "nosplash" and "nomodeset" kernel boot options should be used in /boot/grub/grub.cfg.

QEMU is hypervosor for work and development. It's more powerfull and flexible than Virtual Box.

For better performance QEMU provide paravirtualization drivers for disks and network interfaces called VirtIO. As video card QEMU can USE QXL-video card

Also QEMU provide opensource VDI protocol called SPICE. With SPICE it's possible to work with VM remotely looks like it was launched localy.

VirtIO support is provided by kernel, QXL-support provided by kernel and "xf86-video-qxl" package, SPICE-support provided by kernel and "spice-vdagent" package.

"spice-vdagent" package is not installed by default, because it useless when QEMU hypervisor is not used. Install this package if needed.