[net.unix-wizards] brk's zero-fill behavior on VAXen :-)

ado@elsie.UUCP (Arthur David Olson) (11/06/86)

> > 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.

What's clearly called for is a memory mapping feature that instructs the
hardware to randomize the data in a page once it's been abandoned.  A likely
name would be "Destroy on Deallocation," or, for short, "DoD."  Such a
feature would allow paranoid programs to ensure security without penalizing
other programs.
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ken@rochester.ARPA (Comfy chair) (11/07/86)

Re: hardware support for DoD (Destroy on Deallocation)

Actually this idea was seriously suggested in one of the Multics papers
(if I remember correctly), a hardware line that would reset all bits
in a memory region. I surmise CPU speed has improved so much with respect
to memory speed that this is no longer a significant penalty.

	Ken