Subject: Re: NetBSD on non-MMU systems???
To: Jim Wise <>
From: Todd Vierling <>
List: netbsd-advocacy
Date: 01/08/2002 15:16:27
On Tue, 8 Jan 2002, Jim Wise wrote:

: Motorola 68k processors, for example, have a pretty wide array of
: indirect and PC-relative addressing capabilities.  Using the latter, and
: a compiler configured to emit pointer references as PC-relative memory
: access, a fairly simple-minded fork() (copy the whole damn address
: space) is _certainly_ possible.

Yes.  This requires a modified compiler, as noted in my footnote.  You'd
have to ensure base-relative addressing for:

* data loads/stores
* load effective address (lea) of *code*
* trampolines
* bsr/jsr/jmp/bra

: >[*] The only alternatives are to change the C compiler's notion of a pointer
: >    (not easy, to be sure), or to copy memory around every time a process
: >    context switches.

-- Todd Vierling <>  *  Wasabi & NetBSD:  Run with it.
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