Apart from the standard VESA resolutions, the VirtualBox VESA BIOS allows you to add up to 16 custom video modes which will be reported to the guest operating system. When using Windows guests with the VirtualBox Guest Additions, a custom graphics driver will be used instead of the fallback VESA solution so this information does not apply.
Additional video modes can be configured for each VM using the
extra data facility. The extra data key is called
CustomVideoMode<x> with x
being a number from 1 to 16. Please note that modes will be read from 1
until either the following number is not defined or 16 is reached. The
following example adds a video mode that corresponds to the native
display resolution of many notebook computers:
VBoxManage setextradata "VM name" "CustomVideoMode1" "1400x1050x16"
The VESA mode IDs for custom video modes start at
0x160. In order to use the above defined custom video
mode, the following command line has be supplied to Linux:
vga = 0x200 | 0x160 vga = 864
For guest operating systems with VirtualBox Guest Additions, a custom video mode can be set using the video mode hint feature.
When guest systems with the Guest Additions installed are started using the graphical frontend (the normal VirtualBox application), they will not be allowed to use screen resolutions greater than the host's screen size unless the user manually resizes them by dragging the window, switching to full screen or seamless mode or sending a video mode hint using VBoxManage. This behavior is what most users will want, but if you have different needs, it is possible to change it by issuing one of the following commands from the command line:
VBoxManage setextradata global GUI/MaxGuestResolution any
will remove all limits on guest resolutions.
VBoxManage setextradata global GUI/MaxGuestResolution >width,height<
manually specifies a maximum resolution.
VBoxManage setextradata global GUI/MaxGuestResolution auto
restores the default settings. Note that these settings apply globally to all guest systems, not just to a single machine.