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Old 03-22-2008, 10:47 PM   #1
mnsse
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Fedora Core 8 x86_64 does not recognize full 4GB Ram


Hi,
Have found threads all over the internet but was never able to get the answer I am looking for. So I decided to post my question instead of reading someone else's and get answers specific to my problem.

Problem
I have downloaded Fedora 8 x86_64 ISO (Live CD), burned it on a DVD and inserted it in the DVD Drive and restarted my laptop. Fedora 8 loaded without any problems. I opened up the terminal in Fedora 8 and typed in
free -m. Following it what "free -m" reported:
-------------------------------------------------------------------------
total used free shared buffers cached
Mem: 3014 1366 1648 0 117 709
-------------------------------------------------------------------------

So what is wrong with it? The totally memory being reported is 3014MB where as I expect it to report 4096MB because I have installed 4GBs of RAM in my Laptop.

Results of other commands
----------------------------------------------
[fedora@localhost ~]$ uname -m
x86_64
----------------------------------------------
[fedora@localhost ~]$ getconf LONG_BIT
64
----------------------------------------------
[fedora@localhost ~]$ uname -a
Linux localhost.localdomain 2.6.23.1-42.fc8 #1 SMP Tue Oct 30 13:18:33 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
----------------------------------------------

Other important info
Intel Core 2 Duo Processor T5500 1.66GHz
Installed Ram: 4GB (DDR2 PC2 5300)
Linux Kernel: 2.6.23.1-42.fc8
GNOME: 2.20.1

This laptop came installed with Windows Vista 32 bit which only recognizes 3GB and out of which 1GB is what Windows Vista consumes leaving me with only 2GBs which is not enough for me and the work I do
on this laptop. I would like have some more memory available so I can do my work a little more efficiently. But before installing linux on my hard disk, I thought I should first run the Fedora Core 8 Live CD and see if it reports 4GBs of RAM that is installed in the machine. But Fedora Core 8 did exactly what Windows Vista 32 bit bit. Now I understand that 32 Bit OSes have this limitation and can not make use of all available RAM unless PAE is enabled. I tried PAE on windows VISTA, it did not work for me then I tried enabling both DEP & PAE, I started having problems running applications but still VISTA 32 bit only reported 3GB of RAM, not 4GB.
So I thought I should install 64bit Linux but this did not help either.
I assumed x86_64 indicates a 64bit OS so I downloaded that. Is my assumption incorrect?
If someone could kindly tell me what specific Linux should I get in order to see all 4GBs installed on my machine?, and where to get that particular Linux Version/Flavor/Distro?

I hope all information I provided above was atleast enough for experts to tell that my system is capable of handling 64 bit OS and should not have any problems in making use of all 4GB installed RAM.

P.S.: I hope VMWare images can be run on Linux and 3GB of memory can be assigned to an Image without any difficulty or linux limitation.Because if I cant run VMWare images with 3GB of memory allocated to them, then I don't need to worry about this whole thing.


- SAHM
 
Old 03-23-2008, 12:33 AM   #2
lazlow
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Some of the Intel chipsets cheat and use a 32bit based memory controller, which leaves you with the same situation as running a 32bit OS. If this is the case with your motherboard/chipset you are pretty much just stuck.

You should be able to run VMWare on 3GB.
 
Old 03-23-2008, 12:48 AM   #3
Drakeo
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configure the kernel to 4gig or more=y
 
Old 03-23-2008, 12:53 AM   #4
Drakeo
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LOL you typed free -m and it told you how much memory was free at that instanat second. not bad.Mem: 3014 1366 1648 0 117 709 so add 3014 to 1366 and what do you get ? plus it says your swap was only using 117 at the time. 117 pluss 709 total swap ?
I see all 4 gigs from here
 
Old 03-23-2008, 12:55 AM   #5
Drakeo
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the 64 bit thing has no issue at this type of stuff those are the length of instructions to the cpu 64 to 4th power cool

Last edited by Drakeo; 03-23-2008 at 12:57 AM.
 
Old 03-23-2008, 01:16 AM   #6
mnsse
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Quote:
Originally Posted by Drakeo View Post
LOL you typed free -m and it told you how much memory was free at that instanat second. not bad.Mem: 3014 1366 1648 0 117 709 so add 3014 to 1366 and what do you get ? plus it says your swap was only using 117 at the time. 117 pluss 709 total swap ?
I see all 4 gigs from here

Text alignment messed up a little bit but I think 3014 is total memory, 1366 is currently in use, 1648 is free (not being used).
I am not too sure about SWAP but is there anything else that I can try? I have read about SMP and HUGEMEM, what is all that stuff guys?

Thanks
 
Old 03-23-2008, 01:22 AM   #7
mnsse
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Quote:
Originally Posted by lazlow View Post
Some of the Intel chipsets cheat and use a 32bit based memory controller, which leaves you with the same situation as running a 32bit OS. If this is the case with your motherboard/chipset you are pretty much just stuck.

You should be able to run VMWare on 3GB.

I highly suspect that this is case case with my motherboard. Does it matter if BIOS displays 4096MB as installed memory? Is that an indicator of something? How can find out more about my motherboard? maybe it is the root cause of the entire problem.
Also Drakeo mentioned to configure the Kernel? How do I do that? Is it something as simple as putting some params/values in some configuration file or it is something that requires recompiling the kernel also.
 
Old 03-23-2008, 02:58 AM   #8
lazlow
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The standard 64bit F8 kernel should have no issues with that small amount of memory. If you go above 64GB(?) I think you have to shuffle things around.

I THINK if the memory controller is 32bit it acts just like a 32 bit OS as far as memory. This would fit the missing memory you are seeing.

The motherboard and bios version should show up when you boot (usually during the memory count/check). Other than that you would have to check your laptop specs.
 
Old 03-23-2008, 03:45 AM   #9
syg00
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_64 should be a 64-bit kernel. Seems you've checked things out as well as you could. 64-bit uses a linear (virtual) address space. Presumably this is a motherboard problem as mentioned. Just for info, my XPS (running x64 Ubuntu) shows
Code:
            total       used       free     shared    buffers     cached
Mem:         3962        651       3310          0         17        293
 
Old 03-23-2008, 04:50 AM   #10
mnsse
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Quote:
Originally Posted by syg00 View Post
_64 should be a 64-bit kernel. Seems you've checked things out as well as you could. 64-bit uses a linear (virtual) address space. Presumably this is a motherboard problem as mentioned. Just for info, my XPS (running x64 Ubuntu) shows
Code:
            total       used       free     shared    buffers     cached
Mem:         3962        651       3310          0         17        293

This is what I found about my machine directly from the manufacturer's website
Quote:
Code:
Processor / Speed
 
 Intel® Centrino® Duo mobile technology, featuring:
Intel® Core™2 Duo processor supporting Intel® EM64T
T7200/T7400/T7600 (4 MB L2 cache, 2/2.16/2.33 GHz, 667 MHz FSB) or T5500/T5600 (2 MB L2 cache, 1.66/1.83 GHz, 667 MHz FSB)
Also downloaded a small utility named CPU-Z which has confirmed that CPU supports EM64T.
And I have gone over 100s of webpages, all mentioning pretty much the same thing and that if support for EM64T or AMD64 is present then a 64 Bit OS should detect all memory installed in the machine.
I fully understand what lazlow and syg00 are saying but then why so many people recommending to go 64 bit are failing to mention that having a 64bit CPU is not enough to take advantage of 64 bit OS?

Should I try getting some other distribution/flavor of linux? Such as Ubuntu 64 Bit? I guess
 
Old 03-23-2008, 05:11 AM   #11
lazlow
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If it is the motherboard chipset (and I think it is) then changing distros will not help. The information that you have provided only deals with the CPU, not with the motherboard. I do not believe that the CPU is the problem. It is the chipset(assuming I am correct). Intel shoved through a couple of chipsets (not cpus) that were to be used with 64bit cpus but only had a 32bit bus on the memory chipset. They did this becuase it was cheaper to do and it would have no effect until the motherboard was used with more than 3gb of ram. Since the majority of users are still under 2gb of ram it worked for most of their customers. IF I remember correctly this was with the 945 chipsets.

The reason nobody mentions it is becuase Intel is the only one who has done this (AMD's controller is on the CPU) and it was only a couple of chipset series(basically until people started to scream about it).

Edit: Link to mention of some of this problem: http://www.ifrankie.com/?p=70

Last edited by lazlow; 03-23-2008 at 05:33 AM.
 
Old 03-24-2008, 12:06 AM   #12
mnsse
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Quote:
Originally Posted by lazlow View Post
If it is the motherboard chipset (and I think it is) then changing distros will not help. The information that you have provided only deals with the CPU, not with the motherboard. I do not believe that the CPU is the problem. It is the chipset(assuming I am correct). Intel shoved through a couple of chipsets (not cpus) that were to be used with 64bit cpus but only had a 32bit bus on the memory chipset. They did this becuase it was cheaper to do and it would have no effect until the motherboard was used with more than 3gb of ram. Since the majority of users are still under 2gb of ram it worked for most of their customers. IF I remember correctly this was with the 945 chipsets.

The reason nobody mentions it is becuase Intel is the only one who has done this (AMD's controller is on the CPU) and it was only a couple of chipset series(basically until people started to scream about it).

Edit: Link to mention of some of this problem: http://www.ifrankie.com/?p=70
So, I guess I don't have any options in this case.
If I want more 4GBs or more RAM and 64bit 0S then my only option is to get another Laptop?
Or can I replace my chipset.? I guess replacing will cause many incompatibilities and I may endup spending close to what my laptop is worth at this time.
Any advice on this please...
 
Old 03-24-2008, 12:12 AM   #13
btmiller
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Is there an option in the BIOS to map the PCI/peripheral memory above 4 GB? Many chipsets by defauly map the PCI and other I/O memory below 4 GB for the benefits of 32-bit operating systems. This means that only 3-3.5 GB of the system RAM is actually usable. However, it is usually possible to tell the BIOS not to do this (as mentioned above, some chipsets don't allow this, in which case you are struck).
 
Old 03-24-2008, 12:38 AM   #14
lazlow
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Replacing chipsets on a motherboard (any motherboard) is impossible (for normal people).

I would go ahead and try it with the 3gb (on 64bit). Linux is much better with memory than windows. I regularly deal with 10GB (not MB) images on my box with 2gb of ram, without issue. There really is not any laptop applications out there (that I can think of ) that should have any issues. Anything that will require that much memory will also require more power (cpu) than you have.
 
Old 03-24-2008, 12:41 AM   #15
armanox
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Quote:
Originally Posted by mnsse View Post
So, I guess I don't have any options in this case.
If I want more 4GBs or more RAM and 64bit 0S then my only option is to get another Laptop?
Or can I replace my chipset.? I guess replacing will cause many incompatibilities and I may endup spending close to what my laptop is worth at this time.
Any advice on this please...
Sadly it would seem so. Laptop motherboards are not good for modifying, so replacement would seem to be an order, which, is sad.
 
  


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