Re: [CentOS] x86 uniprocessor 4GB memory

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If this is a different mainboard, then it will probably have different characteristics - you probably need to ask your supplier about it ...

James Pearson

Bruno Sousa wrote:
Hi there,
I did the question regarding multiple processors, because it seems like i
will be getting na HP ML 350 with 2 Intel Xeon with 4 or 8gb of memory.
But will I be able to use 4gb or more?
Thanks,
Bruno Sousa

-----Mensagem original-----
De: centos-bounces@xxxxxxxxxx [mailto:centos-bounces@xxxxxxxxxx] Em nome de
James Pearson
Enviada: quinta-feira, 22 de Junho de 2006 17:18
Para: CentOS mailing list
Assunto: Re: [CentOS] x86 uniprocessor 4GB memory


Hi there,

It seems like the bios of this machine doesn't have any type of
configuration regarding the memory mapping.
I'm already using the kernel-hugemem , but the problem remains.
What else can be done?

By the way, if the machine had more than one cpu, the problem would

remain?

Best regards,
Bruno Sousa

-----Mensagem original-----
De: centos-bounces@xxxxxxxxxx [mailto:centos-bounces@xxxxxxxxxx] Em nome

de

James Pearson
Enviada: quinta-feira, 22 de Junho de 2006 15:54
Para: CentOS mailing list
Assunto: Re: [CentOS] x86 uniprocessor 4GB memory

Bruno Sousa wrote:


Hi there,
I'm currently using CentOS 4.3 (Server edition) in a HP DC 5100 with the
IntelR 915GV chipset, powered by a PIV 3.0GHZ.

Now I'm facing a problem, with memory.
I got myself 4GB of memory, the system bios detects it correctly, but in
Linux can only see around 3.5gb memory. With the default kernel-smp (I use
hyperthread) or with kernel-hugemem , I have the same results.

Is there any way to workaround this issue?


It is probably the 4Gb memory hole issue - various 'things' reserve memory below 4GB so hiding the real memory from the OS.

Your BIOS may have a mapping option to map some of this hidden real memory to above 4Gb - however, you need to use a hugemem kernel to access this memory.


Having multiple CPUs would make no difference. The hugemem kernel would only see this memory if the BIOS could map it to above 4Gb - if the BIOS can't, then there is nothing above 4Gb for the hugemem kernel to see.

A newer version of the BIOS _might_ have added this support ...

James Pearson

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