Running 64bit guest on top of 32 host (Windows/Linux) [closed]

Is it possible to run 64-bit guest OS (linux/BSD), using VirtualBox on 64-bit capable CPU, but when host OS is 32bit? (Host may be linux or windows.)

Will 64bit guest run at full speed or it will be slow (64-bit wide instructions emulated like in qemu)?

If 64bit guest will be full speed, is there some 64-bit microOS inside virtualbox? There should be 64-bit host OS to correctly switch between 32 and 64 bit code.

This question is raised because I want to run several virtualized 64-bit Oses and do a highload test between them.

Answer

From the Virtualbox 2.1.2 User Guide, section 1.6:

64-bit guests

Starting with Version 2.0, VirtualBox also supports 64-bit guest operating systems.

Starting with Version 2.1, you can even run 64-bit guests on a 32-bit host operating system, so long as you have sufficient hardware.

In detail, 64-bit guests are supported under the following conditions:

  1. You need a 64-bit processor with hardware virtualization support (see chapter
    1.2, Software vs. hardware virtualization (VT-x and AMD-V), page 10).

  2. You must enable hardware virtualization for the particular VM for which you
    want 64-bit support; software virtualization is not supported for 64-bit VMs.
    Note: On most systems, the hardware virtualization features first need to be
    enabled in the BIOS before VirtualBox can use them.

  3. If you want to use 64-bit guest support on a 32-bit host operating system, you
    must also select a 64-bit operating system for the particular VM. Since supporting
    64 bits on 32-bit hosts incurs additional overhead, VirtualBox only enables this
    support upon explicit request.

On 64-bit hosts, 64-bit guest support is always enabled, so you can simply install a 64-bit operating system in the guest.

Still seems like a dumb idea.

Attribution
Source : Link , Question Author : osgx , Answer Author : HopelessN00b

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