[CentOS] Re: OS does not see all my RAM

Alex White ethericalzen at gmail.com
Mon Oct 3 15:26:54 UTC 2005

Robin Mordasiewicz wrote:
> My BIOS shows all my RAM, but when I boot up linux it does not see all 
> the RAM
> I have two one GIG sticks of RAM, which show up in my bios, but when 
> typing free, I see that it only shows 256Megs.
> Is there a way to specify the amount of RAM if linux cannot detect this, 
> or how can I fix/tweak the OS to recognize the amount of RAM
> my OS is centos-4-x86_64 on a DELL 1850
> [root at smtcorav02 ~ ]# free
>              total       used       free     shared    buffers     cached
> Mem:        251360     220136      31224          0       3932      64748
> -/+ buffers/cache:     151456      99904
> Swap:       524280          0     524280

You can try doing the following:

edit grub.conf and append this to the second line "mem=2048M"

Of course don't put the quotes in there. I believe this can still 
be passed to the kernel in such a manner. I'm not sure if you can 
pass mem=2G of course I suppose you could try it.

If you don't want to make any permanent changes until you know it 
works, simply reboot and at the grub screen hit a key so you can 
edit. The spacebar should suffice or 'e'. Arrow down to the 
second line and hit 'e' again and place the above mem statment at 
the end.


Alex White

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