LinuxQuestions.org
Support LQ: Use code LQ3 and save $3 on Domain Registration
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Hardware
User Name
Password
Linux - Hardware This forum is for Hardware issues.
Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

Notices

Reply
 
Search this Thread
Old 02-03-2010, 09:48 PM   #1
Jeff91
Bodhi Developer
 
Registered: Jan 2009
Location: Alsip, IL
Distribution: Bodhi and Maemo
Posts: 297

Rep: Reputation: 33
Mint 32bit only sees 2.7gigs of RAM


Is there a way I can get Mint 32bit to see more than 2.7gigs of RAM? I have 4gigs in my system and I was under the impression a 32 bit Linux distro could recognize 3.5gigs of RAM, how abouts would I do this?

Regards,
~Jeff
 
Old 02-03-2010, 11:50 PM   #2
symon1980
Member
 
Registered: Nov 2007
Posts: 57

Rep: Reputation: 16
I would say that you probably have a Graphics Card that Shares the Memory...
there are ways to get a 32 bit O.S to see more than 4 gigs of ram but it requires a fair bit
of tinkering...

http://en.wikipedia.org/wiki/Physical_Address_Extension

but for the easiest solution
You might want to consider installing a 64 bit O.S

Last edited by symon1980; 02-03-2010 at 11:56 PM.
 
Old 02-04-2010, 07:58 AM   #3
Jeff91
Bodhi Developer
 
Registered: Jan 2009
Location: Alsip, IL
Distribution: Bodhi and Maemo
Posts: 297

Original Poster
Rep: Reputation: 33
I don't want my 32 bit OS to see more than 4gigs of RAM, I just want it to see my full 3.6gigs (400 megs is shared to the on board video card). And a 32bit OS should be able to see 3.6gigs.

~Jeff
 
Old 02-05-2010, 01:09 AM   #4
symon1980
Member
 
Registered: Nov 2007
Posts: 57

Rep: Reputation: 16
lol
yeah but what im saying is, that a 32 bit O.S can't see 4 gigs of ram unless you hack it to buggery... you need a 64 bit o.s to see 4 gigs of ram or more.... Usually, a 32 bit O.S can see around 3.2gig or maybe up to 3.5 gigs Ram at the most... in your case, you say you have 400mb shared memory, if thats true your O.S is detecting about 3.1gigs... (are you sure your shared memory is 400mb not 512mb?)
Anyways... its about right.... like I said, your best solution is to install a 64 bit o.s if you want to see and use the rest of the Ram.
 
Old 02-05-2010, 09:40 AM   #5
johnsfine
Guru
 
Registered: Dec 2007
Distribution: Centos
Posts: 5,084

Rep: Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110
Quote:
Originally Posted by Jeff91 View Post
Is there a way I can get Mint 32bit to see more than 2.7gigs of RAM? I have 4gigs in my system and I was under the impression a 32 bit Linux distro could recognize 3.5gigs of RAM,
The amount of ram a non PAE 32 bit OS can see depends on lots of details of the motherboard, the BIOS, the shared graphics, etc. It is not a simple max of 3.5 GB (though that is typical) nor is it the total installed minus only the shared graphics ram.

Quote:
Originally Posted by Jeff91 View Post
I don't want my 32 bit OS to see more than 4gigs of RAM, I just want it to see my full 3.6gigs (400 megs is shared to the on board video card).
4GB of ram requires more than 4GB of physical address space. I'm not sure what physical address space is taken by the shared ram for video. But very likely you need PAE to use all your ram, even though you have less than 4GB of ram.

Quote:
Originally Posted by symon1980 View Post
a 32 bit O.S can't see 4 gigs of ram unless you hack it to buggery.
The PAE kernel is not at all "hack it to buggery". It is a basic well supported feature and works very well. It should be easy on a Mint system to just install the PAE version of the kernel from some Mint or Debian repository.

But first, you might want to check how much (if any) extra ram it will let you use. You should look at the "BIOS-provided physical RAM map:" that should be near the top of
dmesg | less
That will tell you how much ram the BIOS makes available to the OS and where in the physical address space it is.

The last line of the table may look something like
Code:
BIOS-e820: 0000000100000000 - 000000013c000000 (usable)
The 100000000 tells you some of your ram is outside the first 4GB of address space. The 3c000000 tells you how much.

A 64 bit OS or a 32 bit PAE OS are equally good at using that ram. Neither would enable more extra ram than the amount shown on that line. If you don't have that line, you may need to change a BIOS menu setting to get it, or you might already be using all the ram your BIOS will let you use.

Last edited by johnsfine; 02-05-2010 at 09:47 AM.
 
1 members found this post helpful.
Old 02-06-2010, 09:50 AM   #6
ssenuta
Member
 
Registered: Mar 2006
Location: NYS
Distribution: Mandriva-2006
Posts: 116

Rep: Reputation: 16
If you are talking about memory that can be displayed via the "top" or "free" commands & they are not reporting the proper amount of memory, check your kernel .config file to see how "HIGHMEM" is configured.

CONFIG_NOHIGHMEM is not set ...If you have 1GB or less ram
CONFIG_HIGHMEM4G=y ...If you have 1GB to 4GB ram
CONFIG_HIGHMEM64G is not set ...If you have 4GB to 64GB ram

I found that if HIGHMEM is not set properly, Linux won't report your memory properly. I had to re-configure my Kernel-2.6.32.2 to get it to display my 2GB ram.
The configure settings are under Processor Type & Features: High memory support.

I hope this will help.
 
Old 02-06-2010, 10:05 AM   #7
johnsfine
Guru
 
Registered: Dec 2007
Distribution: Centos
Posts: 5,084

Rep: Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110Reputation: 1110
Quote:
Originally Posted by ssenuta View Post
CONFIG_NOHIGHMEM is not set ...If you have 1GB or less ram
CONFIG_HIGHMEM4G=y ...If you have 1GB to 4GB ram
CONFIG_HIGHMEM64G is not set ...If you have 4GB to 64GB ram
I think the limit for CONFIG_NOHIGHMEM not set is 896MB, not 1GB.

The limit for CONFIG_HIGHMEM4G=y is less than 4GB. How much less depends on the motherboard, the BIOS, shared video, etc. The typical with no shared video memory is 3.5GB. But that is just typical, not any kind of standard.

The physical address limit for CONFIG_HIGHMEM64G=y may be 64GB and the actual max ram addressable might be less than 64GB by only the same amount that HIGHMEM4G can address less than 4GB. But the practical limit on ram is around 16GB. Above that, the limit on kernel virtual address space makes Linux unable to use all the ram. There are kludges for a 32 bit OS with over 16GB of ram, but they usually don't make sense to use (vs. switching to 64 bit).

So CONFIG_HIGHMEM64G=y is only appropriate from somewhere less than 4GB to somewhere more than 8GB.
 
Old 04-29-2010, 10:36 AM   #8
Wombat Pete
Member
 
Registered: Apr 2010
Distribution: Starting with Debian. When I've learn it passably well, moving to Gentoo. Opinions are appreciated!
Posts: 69

Rep: Reputation: 16
The

Last edited by Wombat Pete; 04-29-2010 at 10:43 AM.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Upgraded ram to 2gb and debian only sees 1 still AgentD Debian 12 01-24-2009 01:29 PM
Debian etch 32bit with 4+GB RAM izghitu Linux - Hardware 4 04-11-2008 10:30 AM
Debian 64 bit sees only 2GB RAM jay73 Debian 1 08-02-2007 07:27 PM
RHEL4 sees only 1GB out of 4GB RAM saarb16 Linux - General 1 02-21-2006 10:36 AM
howto know how much RAM does my system sees hq4ever Linux - Newbie 4 07-09-2004 01:13 PM


All times are GMT -5. The time now is 05:45 PM.

Main Menu
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration