Subject: Re: NetBSD without MMU ?
To: None <>
From: Matthias Pfaller <>
List: netbsd-ports
Date: 04/17/2002 15:06:44
In article <Pine.WNT.4.43.0204120853350.1248-100000@todd>, (Todd Vierling) writes:
> However, you do have to do some really major evil and hack the compiler to
> make all code PIC-and-then-some (ensuring base register relative addressing
> for all data accesses).

No you don't. minix/x86 used segmentation (just like v7 on the pdp11).
minix/68k used "shadow memory". After a fork the processes data segment was
copied to "shadow memory". When the process switched to running the
shadow memory image was exchanged with the "live" image. This is pretty
expensive, but as soon as you exec, there is no more need for shadowing.

Regards, Matthias
Matthias Pfaller                            Software Entwicklung
marco Systemanalyse und Entwicklung GmbH    Tel   +49 8131 5161-41
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