PAE removal

[CJ_Hudson]

Hi,
Please, how do I remove the PAE kernal which seems to have been installed by default on my computer?
(I had 4 GB of RAM but it wasn't all recognised even WITH PAE. Tried 64 bit, didn't work, long story! I now have 3 GB RAM installed, the maximum it will recognise on my system.)
I am using Natty 11.04
I have run:

dpkg --list | grep linux-image

..and get:

rc linux-image-2.6.35-27-generic-pae 2.6.35-27.48 Linux kernel image for version 2.6.35 on x86
rc linux-image-2.6.35-28-generic-pae 2.6.35-28.50 Linux kernel image for version 2.6.35 on x86
ii linux-image-2.6.38-8-generic-pae 2.6.38-8.42 Linux kernel image for version 2.6.38 on x86
ii linux-image-generic-pae 2.6.38.8.22 Generic Linux kernel image

...and when I type:

sudo update-grub

..I get:

Generating grub.cfg ...
Found linux image: /boot/vmlinuz-2.6.38-8-generic-pae
Found initrd image: /boot/initrd.img-2.6.38-8-generic-pae
Found memtest86+ image: /boot/memtest86+.bin
Found Microsoft Windows XP Home Edition on /dev/sda1
done

Please, is the PAE kernal doing any harm there?
Do I want to remove it, and if so, how?:confused:

[tgalati4]

Post the output of:

free
uname -a

To remove any kernel:

sudo apt-get remove linux-image-2.6.38-8-generic-pae linux-headers-2.6.38-8-generic-pae

Unless you have a motherboard limitation (or perhaps a BIOS setting is wrong), pae is generally harmless and it lets you see all 4 GB instead of ~3.2 GB when 4 GB is installed. 64-bit (amd64) does not need pae--it can already address RAM greater than 4 GB. Only certain processors can use 64-bit.

[CJ_Hudson]

Hi tgalati4,
First, sorry I took so long to respond.

The output of

free

is as follows:

total used free shared buffers cached
Mem: 3094956 984212 2110744 0 53296 520724
-/+ buffers/cache: 410192 2684764
Swap: 4000180 0 4000180

Obviously when I installed my previous version of Ubuntu I set the swap file at 4 G hoping PAE would work. But as you say the Motherboard is restricted, and, quite old!

The output of

uname -a

is as follows:

Linux chris-System-Product-Name 2.6.38-8-generic-pae #42-Ubuntu SMP Mon Apr 11 05:17:09 UTC 2011 i686 i686 i386 GNU/Linux

Even with 4 Gb physical RAM installed the computer could only use 3.1 Gb.
Thanks.

[CJ_Hudson]

Bump

[3Miro]

The 4GB issue sounds like a BIOS limitations.

For the PAE kernel, you can got System -> Admin -> Synaptic Package Manager and then install the generic kernel (non pae). Then reboot into the new kernel to make sure it works. If it works, you can use Synaptic to remove the pae.

[CJ_Hudson]

Thankyou. Please, what is the non-PAE kernal indexed under in synaptic?

[kronick]

linux-image-2.6.38-8-generic

[mcduck]

Thankyou. Please, what is the non-PAE kernal indexed under in synaptic?

linux-generic

(You'll definitely want to install that metapackage instead of just directly installing a certain kernel image version, as the metapackage is the one that makes sure you get all the required packages and that you'll also get updates for your kernel.)

[kronick]

i forgot about that metapackage

[CJ_Hudson]

Okay thanks guys,:KS that should tidy things up a bit.

EDIT: Please, do I also need to change the swap file partition size on the hard drive? It is currently set at 4 GB or thereabouts, so will I need to change it to 3GB? I am not desperately short of disc space under Ubuntu.
Edit 2: .. and please, is a reboot required between uninstalling the PAE kernal and re-installing the original generic kernal?

[kronick]

you don't need to change swap size, however as far as I know linux won't be able to use more than 3 gigs of it.
I could be wrong though

[mcduck]

Okay thanks guys,:KS that should tidy things up a bit.

EDIT: Please, do I also need to change the swap file partition size on the hard drive? It is currently set at 4 GB or thereabouts, so will I need to change it to 3GB? I am not desperately short of disc space under Ubuntu.
Edit 2: .. and please, is a reboot required between uninstalling the PAE kernal and re-installing the original generic kernal?

Install the generic kernel first, before you remove the PAE kernel. A reboot isn't required to do the install, but the geenric one won't be used until you have rebooted.

And no need to resize the swap if you don't need the extra gigabyte of disk space back for now. :)

[CJ_Hudson]

Thankyou very much to you all, that's very helpful.