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Old 01-26-2010, 08:20 AM   #1
miros84
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Debian limited to 4 GB RAM?


Hello
I have debian lenny with these kernels:
2.6.26
2.6.30
2.6.32 trunk
NO one recognize more then 4 GB and BIOS recognize all Ram.
I read about it and the only solution I found is to compile another custom kernel and active support to 64GB RAM.
Is that the unique solution?
Can I just insert some patch to my currently kernel and resolve this problem? (Support more then 4GB)
 
Old 01-26-2010, 08:48 AM   #2
MS3FGX
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Are you on 64 bit hardware? On 32 bit systems, 4 GB of RAM can only be supported through PAE. Your hardware does have to support PAE in the first place though.
 
Old 01-26-2010, 09:03 AM   #3
miros84
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Mi CPU is 64bits.
But My debian..., I dont know.
How can I check it?

Code:
Linux Miros-main 2.6.26-2-686 #1 SMP Wed Nov 4 20:45:37 UTC 2009 i686 GNU/Linux
My motherboard is k10n78

Last edited by miros84; 01-26-2010 at 09:05 AM.
 
Old 01-26-2010, 09:18 AM   #4
MS3FGX
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According to that, you are running the x86 build of Debian. You will need to install the 64 bit version of Debian to reach the full potential of your hardware.
 
Old 01-26-2010, 09:26 AM   #5
miros84
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So. It is not possible to recognize more then 4GB in my computer?
No way?
 
Old 01-26-2010, 09:30 AM   #6
MTK358
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You need the x86_64 version of Debian to do that. You are using the 686 version.
 
Old 01-26-2010, 09:34 AM   #7
i92guboj
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Quote:
Originally Posted by miros84 View Post
So. It is not possible to recognize more then 4GB in my computer?
No way?
Read again the other post above. It's your OS which imposes the limit, not your computer. Either install an x86_64 (64 bits) build of Debian or use an x86 (32 bits) kernel with PAE enabled. The former will require a reinstallation surely, the later will require you to install a capable kernel and allow you retain your current installation. How difficult will that be depends only on one thing: whether Debian provides 32 bits PAE-enabled build of their kernel. A Debian user will be able to answer that better than me.

PS: The info I wrote above assumes that your hardware can work in long mode (64 bits) as you said above. You can check that by doing

Code:
grep flags /proc/cpuinfo
If you see the "lm" flag in the middle of them, then your hardware can do 64 bits.

Last edited by i92guboj; 01-26-2010 at 09:35 AM.
 
Old 01-26-2010, 12:22 PM   #8
the trooper
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Quote:
or use an x86 (32 bits) kernel with PAE enabled
http://packages.debian.org/lenny-bac...o.2-686-bigmem

This would be the quickest and easiest solution.
 
1 members found this post helpful.
Old 01-26-2010, 01:52 PM   #9
miros84
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Quote:
Originally Posted by the trooper View Post
http://packages.debian.org/lenny-bac...o.2-686-bigmem

This would be the quickest and easiest solution.
That sounds smartly

In fact, my hardware is:

Code:
 grep flags /proc/cpuinfo
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch
 
Old 01-26-2010, 01:53 PM   #10
miros84
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What about if I download kernel 2.6.33 from kernel.org, configure it for 64GB support and compile it and install it on my computer.
Will be that another solution?
 
Old 01-26-2010, 02:00 PM   #11
MS3FGX
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You could build another 32 bit kernel with support for PAE, but is there a reason you are trying so hard to run a 32 bit OS on 64 bit hardware?
 
Old 01-26-2010, 02:21 PM   #12
miros84
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Look,
because I have a lot of thing installed on my debian.
I have Virtualbox with meny OS in it.
If I install Debian again, I will have to start everything again.
That's why I move from Windows to Linux.
Because in Linux you dont need to reinstall everytime you have some problem.
 
Old 01-26-2010, 02:22 PM   #13
johnsfine
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Quote:
Originally Posted by miros84 View Post
What about if I download kernel 2.6.33 from kernel.org, configure it for 64GB support and compile it and install it on my computer.
Will be that another solution?
Edit: Oops, I misread your post. You said 64GB and somehow I thought I saw 64bit and answered as if you had said that:
--------------------
Somewhere recently there was a post from someone who said he got something like that to work: Switched from a 32 bit kernel to a 64 bit kernel and switched many other files from 32 bit to 64 bit, but did it all on an existing installed partition of Linux without disturbing all the things that shouldn't change. I didn't understand the details and IIRC, it wasn't a Debian based distribution.

Experts generally say you can't do that. Switching from 32 bit to 64 bit requires reinstalling.

So I won't say for certain you can't switch to 64 bit without reinstalling, but I think you can't switch without reinstalling.

You can switch from 32 bit non PAE to 32 bit PAE without reinstalling, and changing nothing but the kernel package. That is the big advantage of 32 bit PAE fvs. 64 bit.

The only hard part is finding out what name your distribution uses for the 32 bit PAE build of the kernel (it isn't named consistently across distributions). But the trooper seems to have done that task for you.
------------

To get usable 64GB support in 32 bit Linux requires some ugly extra kludges to increase the limit on kernel virtual address space (normally 1GB virtual). Simple PAE is good enough to address 64GB but not good enough to really use 64GB. Up to 16GB, simple PAE is probably enough. Beyond 16GB, reinstalling with 64 bit makes a lot more sense.

I forget which kernel build time option enables PAE vs. which changes the virtual memory relationship to make 32 bit practical for over 16GB. Hopefully you can get PAE without the extra kludge.

Last edited by johnsfine; 01-26-2010 at 02:29 PM.
 
Old 01-26-2010, 03:00 PM   #14
miros84
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I downloaded kernel with 64GB support from backports, I installed it and now my debian recognize my 5GB of RAM.
Happy
 
Old 01-26-2010, 03:29 PM   #15
i92guboj
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Quote:
Originally Posted by miros84 View Post
Look,
because I have a lot of thing installed on my debian.
I have Virtualbox with meny OS in it.
If I install Debian again, I will have to start everything again.
That's why I move from Windows to Linux.
Because in Linux you dont need to reinstall everytime you have some problem.
Not having to reinstall is as good reason as any other, of course.

However, you shouldn't need to change anything you have in your $HOME directory if you migrate to 64 bits, and that includes your VM's. The 64 bits version of VirtualBox should continue to work with your current VM's. To be 100% sure you can always do a 64 bits installation alongside your 32 bits one, and dual boot between them. You can share the home partition (if it's a separated partition) or just copy the contents from the original home directory to the new one on the 64 bits installation, so you don't have to start from scratch.

The OS will need to be reconfigured, though. But on a binary distro like debian that shouldn't be a big deal.
 
  


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