Re: RFC: import of posix_spawn GSoC results

[David Holland <dholland-tech%netbsd.org@localhost>]

On Tue, Dec 20, 2011 at 05:03:51PM -0500, Mouse wrote:
 > > From the annals of the POSIX wars:  the rationale for posix_spawn()
 > > was to support systems without MMUs, where fork() is expensive, and
 > > vfork() impossible.
 > 
 > I would quibble with calling vfork() `impossible'.  Perhaps I'm missing
 > osmehting, but vfork() seems particularly well-suited to such a system
 > to me - the "borrow the VM" semantics strike me as exactly what you
 > want when context-switching is expensive.  (Though of course the `V' of
 > `VM' is a bit of a misnomer in that circumstance.)
 > 
 > In any case, even if I'm wrong, vfork isn't impossible, just, at worst,
 > ludicrously expensive. :-)

No, *v*fork is ~easy with no MMU; you just do nothing with the memory
space at all. It's regular fork that's a problem.

-- 
David A. Holland
dholland%netbsd.org@localhost