[sf-lug] 32bit VS 64bit

Tom Haddon tom at greenleaftech.net
Thu Oct 18 14:25:15 PDT 2007

On Thu, 2007-10-18 at 09:59 -0700, Ernest de Leon wrote:
> You will be missing out on the use of some of the RAM.  Run 'top' from
> the terminal to see how much RAM you system 'sees.'  This will show
> you that you are not using all 4096 MB of RAM.  The reason is that the
> 32 bit address space is not wide enough to address all of the RAM.  In
> addition, every device on the PCI bus takes more addressing space away
> from that.  Realistically, most people with 4GB of RAM in a 32 bit OS
> only see 3.25 to 3.5 GB of usable RAM.

I just installed Ubuntu Gutsy (Server Edition) i386 on a Compaq Proliant
DL580 server with 12GB RAM. It's got quad 700MHz PIII Xeons, so amd64
wasn't an option. "top" reveals 12217548k of RAM.... I did some research
and this seems to explain some of it:


Basically, the limit seems to be per process, not for the entire OS.

On a related subject, I'm getting a message when I boot this server for
F1 to continue, F10 to enter System Partition Utilities. If I try the
latter it says they aren't installed, and it requires me to choose one
before proceeding (so basically you couldn't do unattended
reboots/startups). Anyone have any insight as to what's going on here?

This is on the server that Andy Grimm donated for future SF-LUG
projects, so any help appreciated.

Thanks, Tom


Tom Haddon
mailto:tom at greenleaftech.net
m +1.415.830.6822

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