[CentOS] x86 uniprocessor 4GB memory

[James Pearson]

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 at centos.org [mailto:centos-bounces at centos.org] 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 at centos.org [mailto:centos-bounces at centos.org] 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 A newer version of the BIOS _might_ have added this support ...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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