[TALK] Proving fundamental Unix guarantees

Warren Toomey wkt at tuhs.org
Mon Jun 30 18:13:09 EST 2003

On Mon, Jun 30, 2003 at 05:49:58PM +1000, Chris Maltby wrote:
> On Mon, Jun 30, 2003 at 03:01:09PM +0800, Grahame Bowland wrote:
> > Zeroing pages handed back from an application to the operating system
> > isn't something generally done. Apparently OpenBSD does do it, and
> > FreeBSD zeroes pages when there is system idle time.
> I wonder which pages OpenBSD clears on de-reference? Presumably when
> it's the last reference to an anonymous page. I wonder if they also
> clear any associated swap space?

Well, the 4.4BSD design book says that both the heap and the stack are
zero-filled when new pages are allocated (pg 62, 182). I'd assume that
all the BSds have inherited this behaviour.


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