[CentOS] x86 uniprocessor 4GB memory

James Pearson james-p at moving-picture.com
Thu Jun 22 14:53:51 UTC 2006


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.

James Pearson



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