[Gllug] How much system memory do I have?

[Nuno Pedrosa]

On Thursday 07 May 2009, damion.yates at gmail.com wrote:
> On Thu, 7 May 2009, John Winters wrote:
> > ryan-ir at hai.fi wrote:
> > > Good Day all.
> > >
> > > Last Monday I thought that I would go down to Tottenham Court Road
> > > and buy myself a laptop. I got something but yesterday I started to
> > > wonder about how much RAM this computer actually has - it says 4GBs
> > > on the box.
> >
> > [snip report of different OSs seeing different amounts of RAM]
> >
> > There are two different questions here:
> >
> > 1) How much RAM does my computer have?
> >
> >    Pretty certainly 4 Gigs
>
> lshw should tell you for sure.
>
> > 2) How much RAM can my OS address?
> >
> >    If you're running a 32-bit operating system then you will find that
> > the OS is restricted to anywhere between 3 and 3.5 Gigs.
>
> I'm pretty sure this can be fixed by compiling in PAE

Debian has kernel images with this option: they are the one with bigmem in the 
name. 
I don't know about ubuntu.

> http://en.wikipedia.org/wiki/Physical_Address_Extension
>
> It's just a single option in the kernel config.  However this means
> you're running your own kernel, even if it's built via whatever src
> deb/rpm technique you use rather than a plain tar extract build process,
> you'll always have to remember that you've diverted from the path of
> least resistance.
>
> You /might/ find your dist has a -pae version of the kernel package.
>
> You're much more likely to find that 3GB is fine and not worth the
> effort faffing around compared to...
>
> > Install the 64 bit version of Ubuntu and you will find you can use all
> > your RAM.
>
> This is now a lot less painful than it was.
>
> Damion

N.
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