> I have a server dualPII450 with 1 gig of RAM, and during the boot it says:
>
> Linux version 2.2.7
> #2 SMP Mon May 3 11:23:36 CEST 1999
> Warning only 960MB will be used.
>
> What is that "epsilon" thing, and what is the reason that it doesn't use
> the full amount of RAM?
The address space on ia32 is divided into 3 parts: user space (usually 3
gigs), kernel physical memory mapping and kernel virtual mapping (the
epsilon). Kernel virtual mappings are used for things like mapping PCI
shared memory for device drivers, in addition to fulfilling vremap
requests. In short: it's needed.
> I'm sorry if I should know this.. If so, _please_ point me to the
> documentation.
Alas, it might not be well documented. For 2.3, selecting between 1 and 2
gig support on intel is now a config option, and if it hasn't been
documented yet, it surely will before 2.4.
-ben
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