HowTo Ubuntu 32 bit with 4Gb

[phico]

Hi,

I have a macbook pro with 4Gb RAM.

It was quite simple to make it a pure linux machine as this http://ubuntuforums.org/showthread.php?t=198453

But .. I really wanted to use those 4Gb because I plan to run some virtual machines ...

The solution was to use a 64 bit system .. but .. soon I noticed that
I was 'downgrading' quite everything from 64 to 32 bit because of incompatibilty problems ...

So I looked a little bit more about 32 bit solutions with PAE
(Physical Address Extension)

In a linux kernel it is just a kernel config parameter : CONFIG_HIGHMEM64G

In Ubuntu Desktop kernel it has not been set by default, in Ubuntu Server kernel it has
been set .. but Ubuntu Server kernel is optimized for a Server not for a desktop environement
(no preemption, timer interrupt of 100Hz against 250Hz for the desktop ... )

So the solution was to recompile the kernel.

The problem is my config (as many other) relies on some restricted-modules. There are some information on
the ubuntu wiki about how to recompile those restrited modules for a custom kernel but it is quite a hack of
config files .. not so straightforward.

To keep it simple, I just created a new kernel with same name (abi,flavour..) and so
recompile the restricted module with default config files .. and that's it !


Here it is :

create a work directory

sudo apt-get install linux-kernel-devel fakeroot build-essential

sudo apt-get build-dep linux-image-$(uname -r)
apt-get source linux-image-$(uname -r)

sudo apt-get build-dep linux-ubuntu-modules-$(uname -r)
apt-get source linux-ubuntu-modules-$(uname -r)

sudo apt-get build-dep linux-restricted-modules-common
apt-get source linux-restricted-modules-common

go to linux-xxxx

and edit debian/config/i386/config.generic

(adapt the path to your platform and flavour)

change the folowing lines :

# CONFIG_HIGHMEM4G=y
CONFIG_HIGHMEM64G=y

Now compile kernel and modules

go to linux-xxx

CONCURRENCY_LEVEL=2 AUTOBUILD=1 NOEXTRAS=1 fakeroot debian/rules binary-debs flavours=generic

go to linux-ubuntu-modules-xxx/

CONCURRENCY_LEVEL=2 AUTOBUILD=1 fakeroot debian/rules binary-debs flavours=generic

go to linux-restricted-modules-xxx

CONCURRENCY_LEVEL=2 AUTOBUILD=1 fakeroot debian/rules binary-indep binary-arch

Now install all packages :

go to the root of your working directory

sudo dpkg -i linux-image-xxx-generic_2.6.24-19.34_i386.deb
sudo dpkg -i linux-headers-xxx-generic_2.6.24-19.34_i386.deb
sudo dpkg -i linux-ubuntu-modules-xxx-generic_xxx_i386.deb
sudo dpkg -i linux-headers-lum-xxx-generic_xxx_i386.deb
   
sudo dpkg -i linux-restricted-modules-xxx-generic_2.6.24.13-19.44_i386.deb 
sudo dpkg -i nvidia-glx-new_169.12+xxx_i386.deb

(this is for macbook pro 4. Your platform might have other restricted package to be installed)

Reboot and DO NOT udate your kernel and modules with ubuntu repo's because you will go back to the beginning !

Hope this help you to use your 4 Gigs !

Screnshot in attachment ..