Linux and Non PAE CPU

What is PAE

Physical Address Extension (PAE) is a feature found on almost all 32 bit processors produced after Pentium Pro, ie. younger than around 1995. Because PAE is close to being a standard it is now a requirement for some Linux Distros. During installation the processor is prompted for the PAE flag, and only if present the process will the install carry on. A number of older Pentium M processors produced around 2003-4 (the Banias family) do not display the PAE flag, and hence a normal installation fails. However, these processors are in fact able to run the latest (and PAE-demanding) kernels if only the installation process is modified a little. The problem is not missing PAE, it’s about the processor not displaying its full capabilities. Pentium M’s of the Dothan family display the PAE flag correctly and support the latest distros without modifications. The same distinction (Banias versus Dothan) goes for the lower performing Celeron M processors. In spite of their age many of the affected computers (IBM Thinkpads and Dell Latitudes, for example) are suitable for today’s use if given a light distro.

How to Install my OS

At the Welcome screen of your OS you will need to get to the advanced menu, different flavors have different options. Some will have you press the Tab key, others like Ubuntu will have you press the F6 key, you will see the following line at the bottom of the screen:

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 so it looks like this:

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.

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