[CentOS] 1333/8GB Intel motherboard for C5.1

Tue May 20 17:56:40 UTC 2008
John R Pierce <pierce at hogranch.com>

Linux wrote:
> You are missing the point about the bug in some Intel chipsets.
> http://www.google.com/search?q=intel+chipset+kernel+4gb

or the lack of support in 5.1 for ICH9 in non-AHCI mode which means the 
OS won't even install, never mind 4GB+ memory issues.

so, really there's four completely separate issues here...

A) Intel desktop chipsets don't support 'memory remapping' so somewhere 
between 750MB and 1GB of RAM is physically inaccessible on a machine 
with 4GB+ memory, no matter WHAT you do in software.   This 750MB-1GB of 
inaccessible memory is at the same address as the PCI and PCI-E 
busses.   In a pure 32bit environment, this all has to fit in the first 4GB.

B) many Intel desktop chipsets have a maximum 4GB physical memory 
limitation anyways, which when combined with A) means 3-3.25GB usable 

C)  32bit systems with > 4GB memory require PAE support both in the CPU 
and in the operating system...  /all/ Intel CPUs since about Pentium Pro 
have this.     For systems with > 4GB ram, you probably want to run 
64bit native rather than mess with PAE anyways.

D) out of box support for the chipset and its peripherals so the OS can 
be installed without having to dink around with special flags or add-on 
drivers.   The newest ICH9 and ICH9-R chips ARE supported in 5.1 if they 
are in ACHI mode, but apparently Intel has leaned on motherboard makers 
to not support AHCI mode on ICH9 in the BIOS, only on ICH9-R (which is 
the same basic backend chip with fake-raid enabled).

your 'bug' is issue A).    I think its more a design feature or side 
effect, not an outright bug, but thats a nomenclature thing.