[SLL] Upgrading from 32bit to 64 bit

[Kurt Buff]

On Jan 5, 2008 12:19 PM, Jesse Keating <jkeating at j2solutions.net> wrote:
> On Sat, 5 Jan 2008 11:55:29 -0800
> "Kurt Buff" <kurt.buff at gmail.com> wrote:
>
> > Obviously, Ubuntu doesn't recognize the extra gig of RAM, and I'd like
> > to rectify that situation.
> >
> > I *think* (and am definitely open to correction) that the high-level
> > steps to upgrade would be to update the kernel to 64bit,  and then
> > recompile all of the userland stuff to match. I would not be surprised
> > if I had to get new VMWare licenses for a new 64bit version of that as
> > well.
> >
> > However, I've inherited this box, and am much more of a FreeBSD guy
> > than a Linux person, let alone an Ubuntu devotee.
> >
> > Anyone have experience doing this kind of stuff, and can point me in
> > the right direction?
>
>
> There is a much easier route.  Boot a kernel that has Physical Address
> Extension enabled (PAE).  This allows your 32bit host to see more than
> 4 gigs, usually up to 16 or 32gigs depending on the kernel config.

OK - after poking around a bit, I found a few things:

1) According to Wikipedia, the linux kernel, starting from 2.6, supports PAE.

My kernel definitely is later than that:

     vmware at zdev:~$ uname -a
     Linux zdev 2.6.20-15-generic #2 SMP Sun Apr 15 07:36:31 UTC 2007
i686 GNU/Linux

However, dmesg says, early on:

     [    0.000000] Warning only 4GB will be used.
     [    0.000000] Use a PAE enabled kernel.
     [    0.000000] 3200MB HIGHMEM available.
     [    0.000000] 896MB LOWMEM available.

I've not yet seen how to get that enabled, and google isn't being
helpful. Help appreciated.