Subject: Re: Is -Ttext address changeable - booter interactions?
To: Timm Wetzel <twetzel@gwdg.de>
From: Darrin B. Jewell <dbj@netbsd.org>
List: port-next68k
Date: 02/22/2000 21:01:33
Timm Wetzel  <twetzel@gwdg.de> writes:
> I _think_ that the register dump is not from the booter but from some part
> of the NetBSD kernel, and it shows some 0x438xxxx addresses (isn't this
> where the NeXT booter gets loaded?). 

This is where the rom will start the boot loader, but I don't remember
off the top of my head where the NeXT bootloader will start the kernel.
Currently, the NetBSD kernel expects to be loaded at 0x4000000 as
defined by NEXT_RAMBASE in cpu.h which is memory location 0x0 once
the MMU is turned on.

> Assuming for a moment all this was working correctly, is loading a `-Ttext
> 0' image with the NS booter expected to work at all?

This probably could be made to work, but we may need to change the
RELOC offset used by the kernel before the MMU is turned on.

> Would it perhaps make sense to link the kernel with the start address used 
> by NS and probably expected by the NS booter (0x4000000), and could the
> NetBSD kernel cope with that?

It wouldn't make sense to link the kernel at 0x4000000 without taking
out the RELOC support.  (or setting the RELOC to 0x0)  I also think there
may be other assumptions about the kernel being at the base of virtual
memory, but I'm not sure.

Darrin