Comment 21 for bug 585940

Just to clear up some misinformation. It _is_ possible to address more than 3.2GB on a 32-bit install of Ubuntu.

If you perform a clean install of 9.10 or 10.04 it should detect that you have more than 3.2GB of RAM and install a kernel (PAE) which supports it.

If you upgraded your RAM after installing, or you installed an older version of Ubuntu and then upgraded, you might not have the PAE kernel installed. In that situation just install the package 'linux-image-generic-pae' to address all the available RAM in your computer.

http://packages.ubuntu.com/linux-image-generic-pae

This is a meta package which will pull in the latest PAE kernel for your release. Note this is the current one for Ubuntu 10.04 (Lucid):-

http://packages.ubuntu.com/lucid/linux-image-2.6.32-21-generic-pae

Note from the description: "Geared toward 32 bit desktop systems with more then 4GB RAM."

Note: On some computers this doesn't work, so 64-bit might be better for those people, but for many this does work.