[PLUG] Bigmem not recognizing memory

[Jason Martin]

On Tue, Jul 22, 2008 at 2:50 PM, Bill Barry <bill at billbarry.org> wrote:
> On Tue, Jul 22, 2008 at 2:33 PM, Alan <alan at clueserver.org> wrote:
>
>> On Tue, 2008-07-22 at 13:53 -0700, Bill Barry wrote:
>> > I recently added 4GB of ram to a machine that already had 2GB for a total
>> of
>> > 6GB of memory, but I only see 4GB in  /proc/meminfo.  The bios shows that
>> > the memory is recognized and is functioning, but something is still
>> wrong.
>>
>> It looks like you are using a 32 bit kernel.  Why are you not using a 64
>> bit OS?  It will solve your memory problems. I don't think programs can
>> address more than 3.5 gigs, so adding more is not going to work very
>> well until you upgrade to the correct binaries.
>>
>>
> I am trying to avoid installing a 64 bit OS just because I have lots of
> stuff installed and the shift  might cause problems of its own. I don't need
> the full memory for one application. As I understand it the bigmem kernel
> allows you to use 4GB-64GB with a 32 bit OS. Each process is limited to a
> 4GB address space, but separate processes can be assigned their own  4GB
> space.

I found this link which suggests there might be a problem with the
version of Grub that comes with Debian:

http://howtoforge.org/make-your-xen-pae-kernel-work-with-more-than-4gb-ram-debian-etch-grub

Using PAE your processes still only have 32-bit address spaces, so yes
you can only address 4GB for a single process.

Cheers,
Jason