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Message-ID: <19980718124754.C2575@uni-koblenz.de>
Date: Sat, 18 Jul 1998 12:47:54 +0200
To: Greg Chesson <greg@xtp.engr.sgi.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: wje@fir.engr.sgi.com, adevries@engsoc.carleton.ca, anubis@BanjaLuka.NET,
        linux@cthulhu.engr.sgi.com
Subject: Re: What about...
References: <9807171047.ZM18720@xtp.engr.sgi.com> <m0yxF1A-000aOoC@the-village.bc.nu> <19980718033759.C378@uni-koblenz.de> <9807171858.ZM19563@xtp.engr.sgi.com> <19980718044403.F378@uni-koblenz.de>
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In-Reply-To: <19980718044403.F378@uni-koblenz.de>; from ralf@uni-koblenz.de on Sat, Jul 18, 1998 at 04:44:03AM +0200
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On Sat, Jul 18, 1998 at 04:44:03AM +0200, ralf@uni-koblenz.de wrote:

> On Fri, Jul 17, 1998 at 06:58:07PM -0700, Greg Chesson wrote:

> > I think you'd want to extend the design limit (XKSEG0) beyond 1 TB
> > to handle the next rev of silicon.  I'd suggest 64 TB (48 bits) as
> > the appropriate goal.
> 
> As far as the maximum amount of RAM goes, no problem.  The only assumption
> which I make is that the entire available memory is visible in XKSEG0,
> whatever it's size is.  That means the actual design limit is the maximum
> possible size of XKSEG0 for the MIPS 64bit architecture which is 2^62 bytes.

Ooops, the real limit is of course how much memory can be presented in XKPHYS
which is a bit less, just 2^58 bytes or 4 exabytes.  XKSEG or XKSSEG would
be used for kernel virtual memory which usually isn't used very much under
Linux - it's virtual, but not swappable.

  Ralf