Hello,
I am new to this LQ. Hope, anyone could assists me to solve the problem I have.

Recently, I put a 4GiB (2 x 2 GiB) RAM on Acer Extensa 4620, running Ubuntu 9.04. However, when I click System/Administration/System Monitor
at the Memory and Swap history part, I only can see 2.9 GiB of RAM (memory).

Is this really only 2.9 GiB RAM is being used.

If I would like to have as what installed, 4 GiB, how can I achieve that. Thank you for your response.

Best regards,
++ pit ++

Does your laptop support 4gb of memory?

~Callum

according to the specification, yes it does support (extended upto) 4GiB RAM.

anyhow, I found a solution (but not for notebook) in here
http://www.cyberciti.biz/faq/ubuntu-...tion-solution/

that solution is for HP workstation.

Would it be worked for a notebook (?)
Thank you.

The default Ubuntu desktop kernel does not support PAE, which is needed by the 32bit kernel to address the 4GB of RAM. So far I have only found 3 solutions around this.
1. Run the server kernel instead of the desktop kernel. (Battery life may suffer if this is a laptop)
2. Recompile the desktop kernel yourself to enable this feature.
3. Run the x86_64bit version of Ubuntu. (Which requires your system to support EM64T, Most C2D systems do)

Easiest solution is 1. But best solution is 3.

32-bit or 64-bit ?.
Looks like that uses shared memory for video - that means it is taken from the total RAM.

Even without the video card taking ur RAM. The 32bit Ubuntu Desktop kernel only sees about 3.2GB of RAM. This is a 32bit limitation, it happens on Windows as well.

In your case, your video card probably took an additional 256MB off your RAM leaving you with 2.9GB available. If you take my option 1 & use the Server kernel, it will enable the PAE feature that will allow Ubuntu to address the full 4GB. With this, you might end up with about 3.7GB (your video card still needs RM)

The best solution though is to dump the 32bit Ubuntu & install the x86_64 version of Ubuntu. But make sure your CPU is EM64T capable. Check the specs of your system or you could post the output of # cat /proc/cpuinfo

Yes, I am considering your advice.

But, some words need to be clear first.
What is C2D system ? Don't understand that, please explain. Thank you.

Running x86_64 ubuntu, meaning that I need to change the notebook to the 64-bit architecture (?), since my notebook is 32-bit system. So, this option would not be possible. Am I right ?

I had tried option 1, which is installing the server kernel. It worked. The memory shown was 3.9 GiB. But, I had a problem later on, that FireFox and Opera became not responsive to a mouse scroll up/down. I was not very sure that it was due to the upgrade of the kernel. However, since I was not knowing how to solve it, I returned back to the original kernel by re-installing the system back again.
And, the mouse scroll became normal again. Now, I am back to the state that only 2.9 GiB shown as explained previously.

Option 2, not yet tried.

Thank you for the responses.

Try this from a terminal and post the output (if any) - it will indicate if you have 64-bit capable hardware

got 2 lines of 'lm'

so, is it correct. ? here it is ...

pitanaya@pitanaya-laptop:~$ grep -iow lm /proc/cpuinfo
lm
lm

Ok ...
try to follow your directive.
Here is the result. How should I read it. Thank you.

pitanaya@pitanaya-laptop:~$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Duo CPU T5450 @ 1.66GHz
stepping : 13
cpu MHz : 1000.000
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm lahf_lm
bogomips : 3325.19
clflush size : 64
power management:

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 Duo CPU T5450 @ 1.66GHz
stepping : 13
cpu MHz : 1000.000
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 1
cpu cores : 2
apicid : 1
initial apicid : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm lahf_lm
bogomips : 3325.01
clflush size : 64
power management:

lm flag is long mode which means you can do 64bit.

Sorry about that, I meant Core 2 Duo. As in the Intel chip.

Well, looks like your system is 64bit capable, so I highly recommend installing the x86_64 version of Ubuntu.

Ow ... thank you to you all.
I will try and install x86_64 ubuntu :-)

thank you to @Ongte, @Syg00, @Crito, ... all of you.

Option #2: 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

Welcome to LQ - I guess you were trying to help, but that thread is very nearly a year old.
Dead threads should be left that way.