From owner-freebsd-ppc@FreeBSD.ORG  Tue Jul 25 16:12:28 2006
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Date: Tue, 25 Jul 2006 09:12:05 -0700
From: Peter Grehan <grehan@freebsd.org>
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To: Aditya Godbole <aag.lists@gmail.com>
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Cc: freebsd-ppc@freebsd.org
Subject: Re: link address
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Hi Aditya,

> I'm a bit confused about the link address of the kernel in
> freebsd-ppc. The linker script says its 0x00100000. However on the
> i386 it seems to be 3GB (KERNBASE).
> Does the machine independant code not assume anything about the
> location of the kernel in virtual memory?

  That's right.

  On FreeBSD/ppc, kernel text/data/bss is mapped 1:1 mainly for 
simplicity - the loader's job is a lot easier, and it allows the early 
part of the kernel to run with the MMU disabled if so required.

  The load address is somewhat arbirtrary but it can't be zero since 
that's where vectors live, and boot loader variables are often stored 
below 0x100000.

later,

Peter.