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VirtualBox is cross-platform virtualization software that allows users to run guest operating systems inside a host operating system without having to reboot. Since 2010 VirtualBox software has been written and maintained by the Oracle Corporation.


Term Explanation
Host operating system The host computer. Most likely the physical hardware present in the room. For Gentoo users the host operating system would be Gentoo Linux
Guest operating system The operating system to be installed or currently installed inside the VirtualBox emulation environment. Possible alternative operating systems include Microsoft Windows, Solaris, BSD, Debian, Ubuntu, etc.
VirtualBox Guest Additions Drivers for the guest operating system. These drivers provide smoother operation with the Host operating system compared to the standard drivers installed by the Guest operating system.


There is a source based package (app-emulation/virtualbox) and a binary package (app-emulation/virtualbox-bin) available in the Portage tree. The binary version is available so 64bit no-multilib users can use VirtualBox, too. The binary package contains some extensions which are not available in the source package. To get identical functionality with the source package, emerge it with the extensions USE being enabled.

The qt4 USE controls installation of the graphical user interface (GUI) which is enabled by default.

Since many of the same files are provided by one package or the other, only one virtualbox package can be installed at a time on the same system (either app-emulation/virtualbox or app-emulation/virtualbox-bin. Trying to install them both at the same will with result in a Portage complaining about blockers.

USE flags


USE flags for app-emulation/virtualbox Family of powerful x86 virtualization products for enterprise and home use

alsa Add support for media-libs/alsa-lib (Advanced Linux Sound Architecture) global
debug Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see global
doc Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally global
headless Build without any graphic frontend local
java Add support for Java global
libressl Use dev-libs/libressl as SSL provider (might need ssl USE flag), packages should not depend on this USE flag global
lvm Build VBoxVolInfo that needs devicemapper from sys-fs/lvm2. local
opengl Add support for OpenGL (3D graphics) global
pam Add support for PAM (Pluggable Authentication Modules) - DANGEROUS to arbitrarily flip global
pulseaudio Add support for PulseAudio sound server global
python Add optional support/bindings for the Python language global
qt5 Add support for the Qt 5 application and UI framework global
sdk Enable building of SDK local
udev Controls installation of special USB udev rules. local
vboxwebsrv Build and install the VirtualBox webservice local
vnc Enable VNC (remote desktop viewer) support global


USE flags for app-emulation/virtualbox-bin Family of powerful x86 virtualization products for enterprise as well as home use

additions Install Guest System Tools ISO local
chm Install kchmviewer binary to enable online help (in MS CHM format) local
debug Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see global
headless Install without any graphic frontend local
python Add optional support/bindings for the Python language global
rdesktop-vrdp Install the rdesktop client integration local
sdk Enable building of SDK local
vboxwebsrv Install the VirtualBox webservice local

root #echo "app-emulation/virtualbox-bin PUEL" >> /etc/portage/package.license



root #emerge --ask app-emulation/virtualbox


root #emerge --ask app-emulation/virtualbox-bin

Windows guest-related


When using VirtualBox versions < 5.0.0, it is possible to enable the additions USE when installing VirtualBox on the host system to get the ISO image that contains all necessary Windows guest drivers.


Starting with versions >= 5.0.0, emerge the app-emulation/virtualbox-additions package for Windows guest additions extensions:

root #emerge --ask app-emulation/virtualbox-additions

Linux guest-related

In order to run Gentoo as a guest system, invoke the following command in the Gentoo guest operating system:

root #emerge --ask app-emulation/virtualbox-guest-additions

To enable the shared clipboard, display resizing, seamless mode and drag and drop make sure the user running the session belongs to the vboxguest group.

root #gpasswd -a <user> vboxguest

Changes will not take effect until the user signs out and then signs in again (re-logins).

To install other Linux distributions as guest operating systems please refer to the distribution's documentation on how to install the drivers needed by VirtualBox or consult the official VirtualBox documentation.

VirtualBox shared folders in a Gentoo guest

VirtualBox shared folders can only be mounted after the virtualbox-guest-additions service has been started. Since this happens towards the end of the bootup sequence (OpenRC), a shared folder mount in /etc/fstab will fail. Either:

  • Make the noauto mount option and add a mount/unmount pair of scripts in /etc/local.d
  • View /etc/rc.conf for information about adding extra dependencies for services.

Advanced networking-related

According to the ebuild's message after VirtualBox is installed sys-apps/usermode-utilities and net-misc/bridge-utils can be installed for advanced network configuration. Install them only if advanced networking is required:

root #emerge --ask sys-apps/usermode-utilities
root #emerge --ask net-misc/bridge-utils


Kernel modules

Users will not be able to run and use VirtualBox if they are not a member of the vboxusers group:

root #gpasswd -a <user> vboxusers

Changes will not take effect until the user re-login.

Load the required driver module into the kernel. This module is made available when app-emulation/virtualbox-modules has been emerged:

root #modprobe vboxdrv

Optional modules:

root #modprobe vboxnetadp
root #modprobe vboxnetflt
root #modprobe vboxpci


When using OpenRC it is possible to automatically load the modules each time the system boots. Edit the /etc/conf.d/modules file by adding the following VirtualBox modules:

FILE /etc/conf.d/modules
modules="vboxdrv vboxnetadp vboxnetflt vboxpci"


When using Systemd, a similar approach can be taken. Create a new file under the /etc/modules-load.d directory and list, separated by newlines, the kernel modules to load:

FILE /etc/modules-load.d/virtualbox.conf

Modules can be loaded immediately by running:

root #systemctl start systemd-modules-load

Enable port forwarding to guest machines

When booting LiveCDs or other live media, it can be handy to enable port forwarding from the host machine to the guest machine. None of the additional network configuration modes are necessary to for a simple port forwarding setup, so do not dig too deep into upstream docs. Port forwarding can be handy when running a web server, an SSH daemon, or any other service that runs on a specific port.

First, be sure the guest VM is shutdown, then from the command line issue:

user $VBoxManage modifyvm "VM name" --natpf1 "guestssh,tcp,,2222,,22"

Be sure to replace "VM name" with the proper name of the guest virtual machine. The first number (2222) will be the port on the host machine. The second number (22) will be the port on the guest machine. Adjust accordingly, then reboot the virtual machine. This can also be performed via the GUI by clicking Settings -> Network -> Advanced (drop down) -> Port Forwarding.

More details can be found in the upstream documentation.


There are many options which can influence behavior and performance of the virtual machines. If you don't know what these options are doing, leave them to their defaults. Virtual machines may become unbootable if the wrong options are set.

Here is a list of options that are safe to use:

  • Host I/O cache can safely be enabled for all virtual storage controllers.
  • If the host system's CPU supports hardware virtualization, enable the 'VT-x/AMD-V' option. It can drastically increase the performance of the virtual machines.


virtualbox fails to build

When the app-emulation/virtualbox package fails to build because the javac command cannot be found (even with a Java JDK (Java Development Kit) and a Java JRE (Java Runtime Environment) installed), it is likely the JRE has been set as the default system-vm. JRE packages do not contain javac. Make sure the correct system-vm (JDK) has been selected using the java-config command and then try rebuilding virtualbox. More information can be found in the Installing a virtual machine section of the Java User Guide.

virtualbox-modules fails to build

Some users have issues with the app-emulation/virtualbox-modules package failing to build. This can be caused by an improper kernel/profile configuration. Verify the chosen kernel and the selected profile match each other. For example, if a hardened profile is set, a hardened kernel should be used. If a default AMD64 profile is set, then the default gentoo-sources should be used. Run the eselect command to view the list of profile options:

root #eselect profile list
[1]   default/linux/amd64/13.0 *
[2]   default/linux/amd64/13.0/selinux
[3]   default/linux/amd64/13.0/desktop
[4]   default/linux/amd64/13.0/desktop/gnome
[5]   default/linux/amd64/13.0/desktop/gnome/systemd
[6]   default/linux/amd64/13.0/desktop/kde
[7]   default/linux/amd64/13.0/desktop/kde/systemd
[8]   default/linux/amd64/13.0/developer
[9]   default/linux/amd64/13.0/no-emul-linux-x86
[10]  default/linux/amd64/13.0/no-emul-linux-x86/desktop
[11]  default/linux/amd64/13.0/no-emul-linux-x86/desktop/gnome
[12]  default/linux/amd64/13.0/no-emul-linux-x86/desktop/gnome/systemd
[13]  default/linux/amd64/13.0/no-emul-linux-x86/desktop/kde
[14]  default/linux/amd64/13.0/no-emul-linux-x86/desktop/kde/systemd
[15]  default/linux/amd64/13.0/no-emul-linux-x86/developer
[16]  default/linux/amd64/13.0/no-emul-linux-x86/selinux
[17]  default/linux/amd64/13.0/no-multilib
[18]  default/linux/amd64/13.0/x32
[19]  hardened/linux/amd64
[20]  hardened/linux/amd64/selinux
[21]  hardened/linux/amd64/no-multilib
[22]  hardened/linux/amd64/no-multilib/selinux
[23]  hardened/linux/amd64/x32
[24]  hardened/linux/musl/amd64
[25]  default/linux/uclibc/amd64
[26]  hardened/linux/uclibc/amd64

Then use the eselect command again to display which kernel is selected:

root #eselect kernel list
[1]   linux-3.13.10-hardened
[2]   linux-3.16.3-hardened-r1
[3]   linux-3.17.2-hardened-r1
[4]   linux-3.18.4-hardened
[5]   linux-3.18.5-gentoo *

Looking at the output of these two commands, a user can determine if the system is setup properly (the profile matches the kernel) and should have no issues installing app-emulation/virtualbox-modules. Remember: Make sure the system profile and the selected kernel match!

virtualbox-modules permission denied errors

The following "Permission denied" errors can be caused by a strict file mode creation mask (e.g. umask 077):

cc1: error: ./arch/x86/include/generated/uapi: Permission denied
cc1: error: ./arch/x86/include/generated/uapi: Permission denied
cc1: error: ./include/generated/uapi: Permission denied
cc1: error: ./include/generated/uapi: Permission denied
cc1: error: ./arch/x86/include/generated/uapi: Permission denied
cc1: error: ./include/generated/uapi: Permission denied
cc1: error: ./arch/x86/include/generated/uapi: Permission denied
cc1: error: ./include/generated/uapi: Permission denied

The easiest solution would be to backup .config, run make distclean and use the default umask 022.

Host key failing to operate in the virtual machine

If the host key (typically the right Ctrl key) is failing to operate within the virtual (guest) machine, be sure any desktop environment or window manager hooks to host key have been disabled from the host machine's desktop environment or window manager.

For example, the GNOME 3 desktop environment includes a "Show location of the [mouse] pointer" option in the Keyboard and Mouse section of the Tweak Tool (gnome-extra/gnome-tweak-tool). This option will enable a ripple effect to be displayed around the mouse when either the right or left Ctrl key is pressed. This mouse locator handle conflicts with the virtual machine's handle on the right Ctrl key. Disabling this setting (via switching the rocker switch to Off in the Tweak Tool interface) should fix the problem by re-assigning the right Ctrl key as the handle for the host key within the virtual machine.

Performance problems

Microsoft Windows guests

  • Do not enable APIC for Microsoft Windows guests! VirtualBox also has a bad habit of enabling this option on its own will. The fix is to select the System Processor Driver (i.e. ACPI Uniprocessor PC) and manually upgrade (change) to the Advanced Configuration and Power Interface (ACPI) PC. Shutdown (not reboot), restart VirtualBox and ensure APIC is off, then boot the guest. As usual, always make a backup before playing with Windows.
    Not true for all Windows operating systems. Windows XP and Windows 7 play nice with APIC as long as they got installed with APIC being enabled.
  • Using a SATA controller, it is necessary to choose the right driver version from Intel's SATA drivers. Using a wrong version will cause performance problems along with blue screen errors! Refer to this post for a list of working SATA drivers.
  • Slow performance using SATA driver? Only use the SATA controller interface for the hard disk. Remove any CDROMs from the SATA controller and place them onto a IDE Controller.
    This can also be a problem of using the wrong SATA-driver version.
  • When installing the VirtualBox Guest Additions into your Windows operating system, do not select to enable Direct3D (experimental) option as this will cause resizing problems and other anomalies. Also, you need to install the Guest Additions from Safe Mode.
  • Do not use the ICH9 chipset with Windows. It is still considered experimental. Using it can cause temporary freezes of the whole VM when used with Windows 7. See this post for more informations.
  • Slow read/write speed to the virtual disk? If the host system has sufficient RAM, try checking (enabling) the Use Host I/O Cache check box in the virtual machine's Storage frame. This will cache much of the guest machine's page file into the host's memory effectively limiting the amount of I/O guest machine will use the virtual disk image file. This is particularly helpful when running Windows guests because of the amount of paging Windows based operating systems regularly perform.

Linux guests

  • When running Gentoo as a guest system make sure you start the virtualbox-guest-additions init script during bootup.

Kernel driver not installed

VirtualBox-Error: Kernel driver not installed

This may occur after building a new kernel and causes an error message:

user $VirtualBox
WARNING: The vboxdrv kernel module is not loaded. Either there is no module available for the current kernel (4.9.0-gentoo) or it failed to load. Please recompile the kernel module and install it by

for m in vbox{drv,netadp,netflt}; do modprobe $m; done

You will not be able to start VMs until this problem is fixed.

Solution: Rebuild the VirtualBox kernel modules via:

root #emerge --ask --oneshot @module-rebuild

The system may need rebooted for changes to take effect.

Nonexistent host networking interface, named 'vboxnet0'

root #VBoxManage hostonlyif create

Newly created interface will now be shown as available, but not activated (down):

user $ifconfig -a

An IP will need to be assigned to it:

root #VBoxManage hostonlyif ipconfig vboxnet0 --ip

Kernel Panic when suspending the HOST while Virtualbox is running

If you experience such behavior, try removing the vbox family of modules before suspending. If this solves the kernel panic, you can add the vbox modules to the list of permanently removed modules before suspend, these modules are loaded automatically after suspend:

root #echo 'SUSPEND_MODULES="vboxpci vboxnetflt nboxnetadp vboxdrv"' >> /etc/pm/config.d/gentoo

See also

  • phpVirtualBox - Web-based administration utility (PHP)
  • QEMU - A popular open source virtual machine emulator.
  • VMware - A popular closed source virtual machine emulator.

External resources