[rhelv6-list] RHEL6 x86 on system with 4 GB memory

[Jonathan M. Polom]

On Tue, May 3, 2011 at 8:26 AM, Jonathan M. Polom
<s0nic0nslaught at gmail.com> wrote:
> On Tue, Apr 19, 2011 at 2:58 PM, Steve Allen
> <allen at doobie.itdl.ds.boeing.com> wrote:
>> "Jonathan M. Polom" <s0nic0nslaught at gmail.com> wrote:
>>> I have Red Hat 6 x86 installed on a Pentium 4 system with 4 GB system
>>> memory. Although the default kernel has PAE capability (no modules in
>>> lsmod but it's a requirement for the x86 variant so it's likely
>>> compiled in) it claims total system memory is about 3.3GB (via top or
>>> gnome performance monitor). How do you get RHEL6 to see >= 4GB memory?
>>> Is it a kernel argument or something else?
>>
>> PAE has to be enabled in the BIOS.  If you don't have that option in the
>> BIOS, you just can't do it.  I'm in the same position, 4GB RAM, but no
>> PAE in the BIOS, so all I get available is about 3.3GB.
>>
>> Steve
>>
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>>
>
> Didn't think to check the BIOS. Will do. Thanks.
>
> --
> Jon Polom
>

Sorry for resurrecting a dead thread but I just rechecked this issue.
The BIOS reports 4.0GB of memory installed but doesn't appear to have
an option to enable/disable PAE. So perhaps PAE isn't supported by the
BIOS? Or PAE is enabled by default. This is something I need to check
with my system vendor, however it still seems odd. Why would the BIOS
report 4.0GB of installed memory without being able to use all 4.0GB?
A colleague mentioned that it has to do with how the BIOS calculates
installed memory: installed memory size is calculated by the BIOS by
taking the difference between the highest and lowest memory addresses.
Is it typica for a BIOS to report 4.0GB (beyond the 32bit max address
without PAE) yet not support PAE?

Thanks,
Jon