Blog :: More than 4Gb RAM on Ubuntu 32 bit

I recently grabbed some more RAM since my desktop PC had only 3Gb. I'm running the most recent LTS release by Ubuntu, Lucid Lynx 10.04.

I removed a 1 Gig stick and added two 2 Gig sticks I bought from Newegg. My bootup POST showed 6 gigs recognized but when I got back into Ubuntu top and `cat /proc/meminfo` agreed that I had less than 4 gigs.

Of course I immediately figured out that this was because of the 4 gig limitation on addressing memory common to 32bit operating systems. I wasn't up for updating to 64bit Ubuntu over my lunch break so I googled to see if there were any other options and Ubuntu's own documentation pointed me in the direction of Physical Address Extension - a different kernel that would allow addressing more than 4 gigs of memory. There are various limitation so I may yet go x64 but this sounded like something I could still get done on my lunch break. A quick

sudo apt-get install linux-generic-pae

and a reboot and I had a new kernel that recognized all 6 gigs of my RAM. Of course... now my Nvidia drivers didn't work. I didn't discover till later that there's an easier way to solve this (see this thread) but what I ended up doing was manually downloading the drivers from Nvidia and recompiling them (see this post for instructions on compiling the Nvidia drivers). For future reference it apparently works to remove the linux-headers-generic package and install linux-headers-generic-pae, than use System -> Administration -> Hardware drivers to reinstall the Nvidia packages. Either way - it is possible to end up with more than 4 Gigs of RAM on a working 32bit Ubuntu

Posted on May 20th 2011, 06:29 PM