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Date:      Sun, 26 Jan 1997 22:44:28 +0100 (MET)
From:      Luigi Rizzo <luigi@labinfo.iet.unipi.it>
To:        dg@root.com
Cc:        phk@critter.dk.tfs.com, swallace@ece.uci.edu, current@FreeBSD.ORG
Subject:   Re: exec bug
Message-ID:  <199701262144.WAA28837@labinfo.iet.unipi.it>
In-Reply-To: <199701262132.NAA08152@root.com> from "David Greenman" at Jan 26, 97 01:31:59 pm

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> >Wouldn't it make sense for the image activator to do a couple of probes
> >first to see that the data is actually available ?  that way it could
> >fail intelligently ?
> 
>    The problem is that determining page residency might be too high of an
> overhead, but maybe not. See my last reply to Bruce.

how about this:

	int dont_panic_just_probing= 0;

	...
	s = splhigh();
	dont_panic_just_probing = 1;
	... access page at address p ...
	if (dont_panic_just_probing == 2 && fault_virtual_addr == p)
		could_not_get_the_page = 1;
	dont_panic_just_probing = 0;
	splx(p);

dont_panic_just_probing is checked in the page fault handler, if set to
1 is incremented to 2, otherwise just do as it is now.

	Luigi



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