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I'm trying to install Redhat 5 on my virtual box which is running on Ubuntu 12.04. But when ever I try to install it show this message.

VBox screen

To make sure that my CPU supports long mode I ran this command

cat /proc/cpuinfo

and it shows in flags section that my cpu is LM

enter image description here

and also VIRTUALIZATION is enabled in BIOS.

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It seems, regardless of your real host CPU, the emulated guest CPU isn't 32-bit. Do you get a choice when you create the virtual machine? – RedGrittyBrick Oct 1 '12 at 9:31
up vote 2 down vote accepted

64-bit guests

VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems,[11] provided that the following conditions are met:

  • You need a 64-bit processor with hardware virtualization support (see the section called “Hardware vs. software virtualization”).

  • 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.

  • 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 (which typically come with hardware virtualization support), 64-bit guest operating systems are always supported regardless of settings, so you can simply install a 64-bit operating system in the guest.


On any host, you should enable the I/O APIC for virtual machines that you intend to use in 64-bit mode. This is especially true for 64-bit Windows VMs. See the section called “"Advanced" tab”. In addition, for 64-bit Windows guests, you should make sure that the VM uses the Intel networking device, since there is no 64-bit driver support for the AMD PCNet card; see the section called “Virtual networking hardware”.

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It is giving you the advice to use a 32 bit disctribution, did you try that out? Or do you really need a 64 bit distribution.

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well than I have to download 32 bit distribution. And I don't wanna do that. – OmiPenguin Oct 1 '12 at 7:50

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