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From: campbell@maynard.UUCP (Larry Campbell)
Newsgroups: net.unix-wizards
Subject: Re: brk's zero-fill behavior on VAXen
Message-ID: <404@maynard.UUCP>
Date: Mon, 3-Nov-86 07:54:49 EST
Article-I.D.: maynard.404
Posted: Mon Nov  3 07:54:49 1986
Date-Received: Tue, 4-Nov-86 04:59:47 EST
References: <7208@elsie.UUCP>
Reply-To: campbell@maynard.UUCP (Larry Campbell)
Organization: The Boston Software Works Inc., Maynard, MA
Lines: 16

In article <7208@elsie.UUCP> ado@elsie.UUCP (Arthur David Olson) writes:
>In section 2 of the UNIX Programmer's Manual, the description of the "brk" and
>"sbrk" calls note only that they change the system's notion of the lowest
>location not used by the program.  If the result of the call is to expand the
>address space of the process, there's no promise about the contents of the
>newly-available address space.  Yet on our VAX (and on yours, too, if you
>have one) the newly-available space is always zero filled.
>
>Can system performance be improved by avoiding zero filling of the new
>memory?

Yes, a little bit, but this would be an obvious security hole.
-- 
Larry Campbell       MCI: LCAMPBELL          The Boston Software Works, Inc.
UUCP: {alliant,wjh12}!maynard!campbell      120 Fulton Street, Boston MA 02109
ARPA: campbell%maynard.uucp@harvisr.harvard.edu     (617) 367-6846