Re: Memory on new computer

[Paweł Brodacki <pawel.brodacki@xxxxxxxxx>]

2012/7/16 Martín Marqués <martin.marques@xxxxxxxxx>:
> I had a problem with my main board and CPU and had to buy a new one.
> Also memory, as the old computer had DDR2 memory.
>
> Th problem is that I see only 3.5Gb of memory, while I had a 4Gb bank
> put in the Motherboard (the motherboard says it can handle up to 32Gb
> or ram).
>
> I saw this in dmesg:
>
> [    0.000000] Memory: 3491896k/4702208k available (6177k kernel code,
> 1053240k absent, 157072k reserved, 7004k data, 1004k init)
>
> Why do I get this:
>
> $ free
>              total       used       free     shared    buffers     cached
> Mem:       3513412    2591976     921436          0       8332     914584
> -/+ buffers/cache:    1669060    1844352
> Swap:            0          0          0
>

There are several possible factors:
1) Integrated video card, which uses system memory.
2) Peripheral devices I/O regions are mapped below 4 GB, shadowing the
physical ram.

Here is (old, but still valid) explanation given by IBM for their
servers: https://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-4E4RRF
and here's the same issue addressed by Microsoft:
http://support.microsoft.com/kb/978610
I did not manage to find Red Hat's take on the issue.

In short: Works as designed. You may try to disable devices you do not
use to salvage some address space, but you won't reach 4096 MB
available.

>
> --
> Martín Marqués
> select 'martin.marques' || '@' || 'gmail.com'
> DBA, Programador, Administrador
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