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Date:      Tue, 18 Jun 1996 17:21:35 +0900 (JST)
From:      Michael Hancock <michaelh@cet.co.jp>
To:        "Jordan K. Hubbard" <jkh@time.cdrom.com>
Cc:        hackers@freebsd.org
Subject:   Re: vfork cow? 
Message-ID:  <Pine.SV4.3.93.960618170954.9391A-100000@parkplace.cet.co.jp>
In-Reply-To: <2019.835074726@time.cdrom.com>

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On Mon, 17 Jun 1996, Jordan K. Hubbard wrote:

> Uh, vfork() has always used COW semantics - it just shared data space
> with the parent in the early days and was considered dangerous if you
> had an application which vfork()'d but didn't exec() right away,
> hanging around and changing variables instead.  Nowadays it's a bit

In the historical vfork() the child process was free to modify the
contents of the parent's space and even change the size of the address
space when the child had control of it.  This isn't COW.

> different whereas fork() uses COW semantics by default and neither
> *fork() shares its parent's data space (for that, see rfork(2) in
> -current).  In this environment, vfork() loses its reason to exist.
> 
> 					Jordan
> 




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