Dual Opterons don't see all memory

[Wojciech Puchar]

> I've recently taken ownership of a server (dual Opterons) in my research 
> group.  Whereas it was previously running linux, it is now running FreeBSD. 
> Everything seems to be going great, except linux was able to make use of it's 
> 6GB of memory, and FreeBSD can only see about 4GB of it.
>
> Can anyone help me figure out how to make use of the missing GB?

use FreeBSD/amd64 not i386.