Ubuntu – Virtualbox install 12.04 guest: “pae not present”

paesoftware installationvirtualbox

I get this message while trying to install Ubuntu 12.04 as a guest in VirutalBox 4.1.18, on an Ubuntu 10.04 host.

This kernel requires the following feature not present on the CPU: pae

Some host specs:

The host's kernel is: Linux 2.6.32-41-generic-pae GNU/Linux
lscpu (host): Architecture: i686, CPU op-mode(s): 32-bit, 64-bit
grep --color=always -i PAE /proc/cpuinfo does show pae in its output.

The 12.04 iso used is: ubuntu-12.04.0-desktop-i386.iso

As a comparison/check, I downloaded and installed Linux Mint 13 Cinnamon to the same host on the exact same VM (I just changed the .iso image). It worked fine. Its iso is: linuxmint-13-cinnamon-dvd-32bit.iso

It seems (to me) that I have pae.. what is going on here?

Update: I had assumed that Linux Mint also required pae (being Ubuntu based), but I've just run; grep --color=always -i PAE /proc/cpuinfo in the Mint VM. It showed no output. So it seems the issue may lie with VirtualBox. If that is the case, how can I get Virtualbox into pae mode?

Best Answer

On VirtualBox Manager, open your virtual machine configuration then select System on the left side and open the Processor tab. Be sure that Enable PAE/NX is checked.

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For commandline

VBoxManage modifyvm <VM_name> --pae on

Related Solutions

Ubuntu – How to run a 64-bit guest in VirtualBox

In order to be able to run a 64-Bit system in a VirtualBox, you need a cpu which supports virtualization. AMD calls this function AMD-V, Intel uses VT-x. The Wikipedia explains this quite good. There are a couple of Pentium-4 CPUs which are able to run a 64-Bit OS, but don't offer this VT-x technologie. You can check your system by...

$ egrep '(vmx|svm)' /proc/cpuinfo
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx cid cx16 xtpr lahf_lm
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx cid cx16 xtpr lahf_lm

If you don't get any output, you're not able to run a 64-Bit OS as guest inside your VirtualBox. But don't forget to check your BIOS settings. You might be able to activate these AMD-V/VT-x features inside the BIOS of your computer.

And finally there's a checkbox inside the VirtualBox-Settings. Start VirtualBox, select the virtual machine where you want to run your 64-Bit OS and go into the settings of this VM. Look for "Settings -> System -> Acceleration" and make sure that "Enable VT-x/AMD-V" is activated.

Ubuntu – How to install on a non-PAE CPU? (error “Kernel requires features not present on the CPU: PAE”)

The error message means that your CPU does not support PAE extensions - that is a technique which allows a 32bit CPU to address more than 4GB of memory address space.

By default, 12.04 and later versions of Ubuntu expects a CPU with this capability:

PAE is provided by Intel Pentium Pro and above CPUs, including all later Pentium-series processors (except the 400 MHz-bus versions of the Pentium M). It is also available on other processors with similar or more advanced versions of the same architecture, such as the AMD Athlon[dubious – discuss] and later AMD processor models. wikipedia

While the above is strictly true, old systems which have the memory controller on the motherboard may not "expose" the CPU's PAE support, effectively making them non-PAE.

There is a heated bug report about this; Canonical has decided that the default Ubuntu Desktop install will expect PAE support.

A few suggested workarounds:

Workaround 1: Install Lubuntu or Xubuntu, then install the regular Ubuntu Desktop

Install either Lubuntu 12.04 32-bit or Xubuntu 12.04 32-bit; both of these use a non-PAE kernel by default.
Once you boot into your new Lubuntu/Xubuntu, you can then switch to the default Unity desktop by installing the ubuntu-desktop package.

Workaround 2: Install an older version and then upgrade to 12.04

Install 10.04 or 11.10 and then upgrade to 12.04. See the linked question below for 12.10.

Workaround 3: If you have a wired internet connection, use the "net install" mini-CD

You will need a reasonably fast wired connection for this method -- all packages will be downloaded over the internet.
Download the non-PAE netboot CD image mini.iso and burn it to a CD or USB.
Boot from it, follow the steps, and choose linux-generic when asked to choose a kernel, and ubuntu-desktop to get the "default" Ubuntu installation the regular Desktop CD would have given you, just with a non-PAE kernel.
- You can also choose one of the other desktops. You should choose a desktop otherwise you will not have a GUI to play with after installation.

Workaround 4: Ubuntu 12.04.5 and 14.04 (or later) on Pentium M only

Ubuntu 12.04.5 and 14.04 support an option ("forcepae") to enable PAE on Pentium M CPUs (where it is disabled by default). To enable it:
- Boot the 32-bit Ubuntu (or Xubuntu etc.) installer
- When the image of the keyboard and little man in circle appears hit the Tab key
- "Choose your language" popup appears. Use the cursor keys and hit the Enter key to choose your language
- Press F6, a grey menu will popup with some boot options
- Press escape to close the window
- You will now see a line that says:
Boot Options file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash --

Edit this line and add the forcepae parameter with spaces twice around the -- at the end:

Boot Options file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash forcepae -- forcepae
- forcepae -- forcepae note:
  
  forcepae is required twice because it sets the boot parameters for two different kernel boots - the kernel that runs as part of the installer (left of --), and the kernel that runs on the installed system (right of --).
  
  The text at the end should be -- forcepae not --forcepae. There is a space between -- and forcepae
- Hit the Enter key, hopefully Ubuntu will boot and the rest of your install will be successful. If you have graphical problems with Unity, or just find it slow, try a more lightweight distribution like Xubuntu.

Linked Question: