4 G of RAM under 32bit Ubuntu

[madcow]

Install PAE enabled kernel

Open terminal and type the following command:
$ sudo apt-get update
$ sudo sudo apt-get install linux-headers-server linux-image-server linux-server

Once kernel images installed, just reboot your workstation, type:
$ sudo reboot

[yak]

What ThinkPad have you tested this on? Because it certainly won't work on all of them...

A tip: always provide as much info as possible if you post such thing.

[madcow]

You are right.

This assumes that your bios supports 4 G or more.

This will work with Thinkpad with newer chipset (x61, t61, r61, and up).

[maciejs]

Very nice! (-:

I, however, decided to go for 64bit version since from what I have heard server kernel is optimized in a different way than desktop kernel which may result in decreased performance in certain scenarios. Obviously it is not an option when you have 32bit CPU but machines with 32bit CPU and 4GB of RAM are not that common...

I did not have any serious trouble with 64bit OS apart from not being able to install few relatively obscure pieces of software but that was not something I could not live without (-;

Good tip nonetheless, thanks

[gongo2k1]

There shouldn't be any performance degradation using the bigmem kernel, though it's worth noting the following things:

1. The chipset has to be able to address more than 4Gb of memory.
2. The chipset should have a memory remap function available in BIOS. This allows you to reclaim the address space lost to MMIO by hoisting it up to the 64Gb region.
3. Most 32-bit drivers are NOT Large Address Aware so do not enable 64-bit address space for PCI resources from the BIOS. Specifically, the 32-bit Nvidia drivers will not function if the motherboard assigns resources higher than 4Gb. It's better to just use the memory remap function above, the performance hit isn't bad.
4. It's still a 32-bit operating system so no single process can have more than 4Gb address space (unless it's LAA and then it'll use PAE to page in and out of the various 4Gb segments, but almost no 32-bit software does this).


I'm using 8Gb ram right now in a 32-bit environment (Debian Lenny) and it's helpful for running VMs and the extra memory is used as system cache for disk reads and such.