4gb ram on 32bit system

[grobar87]

Hi,
I installed debian 12 32bit on an old dell optiplex gx280 with 4gb of ddr2 ram but the system only reads 3gb.
Is there any way to use whole ram memory?
Thanks.

[oswaldkelso]

https://en.wikipedia.org/wiki/3_GB_barrier

Linux or certain versions of Windows Server and macOS that allow use of Physical Address Extension (PAE) mode on x86 to access more than 4 GiB of RAM.

[arzgi]

Linux reserves some memory for buffering.

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free -h
               total        used        free      shared  buff/cache   available
Mem:           7,7Gi       2,3Gi       4,8Gi       318Mi       1,1Gi       5,4Gi
Swap:          7,4Gi       415Mi       7,0Gi

[LloydLynx]

It's the physical chipset in your computer that's the limitation, not the OS. I've seen this with old Intel hardware.

[fabien]

It's the physical chipset in your computer that's the limitation, not the OS.

Possible. In this case, the BIOS should report 3 GB.

[grobar87]

It's the physical chipset in your computer that's the limitation, not the OS.

Possible. In this case, the BIOS should report 3 GB.

Bios report 4GB.

[lindi]

Hi,
I installed debian 12 32bit on an old dell optiplex gx280 with 4gb of ddr2 ram but the system only reads 3gb.
Is there any way to use whole ram memory?
Thanks.

Are you using a PAE kernel? Run

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uname -a

to check.

[sunrat]

Post output of

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free -m

and

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free --giga

As posted above, free -h may be misleading. Here it shows 15Gi for 16GB RAM.

[CwF]

Some utilities will get the totals wrong. To check if the system is seeing the memory

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$ grep MemTotal /proc/meminfo

One thing to be careful of is zramswap. It will size according to MemTotal but will swap with reference to the 'single process max' of ~3.5GiB.

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$ uname -a & free -h
[1] 27780
Linux user 6.1.0-10-686-pae #1 SMP PREEMPT_DYNAMIC Debian 6.1.38-1 (2023-07-14) i686 GNU/Linux
               total        used        free      shared  buff/cache   available
Mem:           7.8Gi       1.8Gi       5.8Gi       217Mi       1.1Gi       6.0Gi
Swap:          255Mi          0B       255Mi