3.5GB memory limit? (fwd)

[Eric W Biederman]

Kimon Berlin <kimon at hp.com> writes:

> At 12:12 PM Tuesday 2002-09-24, Bob Drzyzgula wrote:
> >Not that the 3.5GB thing is a surprise, but what chipset
> >were they talking about?
> 
> You'll run into something similar regardless of the chipset. 32-bit PCI cards
> need MMIO below 4GB, so a chipset must provide a memory hole for them.
> A "nice" chipset will allow you to remap the affected memory above 4GB, and a
> "nice" operating system will allow you to use that remapped memory.

You can usually do a little better than 3.5GB if you only have a few
pci cards or pci cards with a small mmio hole.  

With a single quadrics card plugged into the E7500 I can still keep
my hole down to 3.5GB.  As far as I know the E7500 is either the only,
or at the very least one of the very first chipsets to offer a remapping
ability.

As far as accessing remapped memory.  That is really dealing with memory
about 4GB.

Eric