VirtualBox inside VirtualBox
Perform these steps on the host (<code>L0</code>).
'''1.''' Power off the VM (<code>L1</code>) if running.<br />
'''2.''' Change the host key.
* <code>VirtualBox</code> → <code>Preferences</code> → <code>Input</code> → <code>Host Key</code>.
* The "outside" (<code>L0</code>) and the "inside" (<code>L1</code>) Host Key must differ, otherwise you can not leave the "inside" (<code>L1</code>) VM anymore.<br />
'''3.''' Enable nested virtualization.
* <code>VirtualBox</code> → <code>click a VM</code> → <code>Settings</code> → <code>System</code> → <code>Processor</code> → <code>Enable 'Nested VT-x/AMD-V</code> → <code>OK</code> (If that does not work, see footnote.) <ref>
Replace <code>Whonix-Workstation-Xfce</code> with the actual name of the VM, for example if the VM was renamed or multiple {{project_name_workstation_long}} are in use.The following command works on Linux. It is untested on Windows but it should be possible to make this command work. Its purpose is adding VBoxManage to PATH (if that is not the default) or using the full path to VBoxManage.
VBoxManage modifyvm Whonix-Workstation-Xfce --nested-hw-virt on
'''4.''' Assign less virtual CPUs.
For example if the host has 4 physical CPU cores, reduce the VM to 3: <ref>
https://www.virtualbox.org/ticket/19500
* <code>VirtualBox</code> → <code>click a VM</code> → <code>Settings</code> → <code>System</code> → <code>Processor</code> → <code>Reduce to 3</code> → <code>OK</code><br />
'''5.''' Increase virtual RAM.
* <code>Virtual machine</code> → <code>Menu</code> → <code>Settings</code> → <code><i>Adjust</i></code> <code>Memory slider</code> → <code><i>Click:</i> OK</code><br />
'''6.''' Using I/O APIC can speed up the VM.
* <code>VirtualBox</code> → <code>right-click on VM</code> → <code>Settings</code> → <code>System</code> → <code>check "Enable I/O APIC"</code> → <code><i>Click:</i> OK</code> <ref>
vboxmanage "{{project_name_workstation_short}}" modifyvm --ioapic onSo does enabling ACPI. Enabling ACPI in all VMs significantly speeds up the "inside" VM (<code>L1</code>).
vboxmanage "{{project_name_workstation_short}}" modifyvm --acpi onQuote [https://www.virtualbox.org/manual/ch03.html#settings-motherboard VirtualBox manual]:
ACPI is the current industry standard to allow OSes to recognize hardware, configure motherboards and other devices and manage power. As most computers contain this feature and Windows and Linux support ACPI, it is also enabled by default in Oracle VM VirtualBox.
These settings are in use for {{project_name_short}} VMs by default.'''7.''' Power on the VM (<code>L1</code>).
Perform these steps inside the VM (<code>L1</code>).
'''1.''' Install VirtualBox.
'''2.''' It should now be possible to use VirtualBox inside the VM (<code>L1</code>).<br />
'''3.''' Make CPU core adjustments.
If the VM (<code>L1</code>) has 3 "physical" (actually virtual) CPU cores do not assign more than 2 virtual CPU cores to VM (<code>L2</code>). Start with 1 virtual CPU for the VM (<code>L2</code>). If that performs well, consider experimenting with an increased number:
* <code>VirtualBox</code> → <code>click a VM</code> → <code>Settings</code> → <code>System</code> → <code>Processor</code> → <code>Increase to 2</code> → <code>OK</code>
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