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Date:      Fri, 30 Apr 1999 20:24:28 +0200
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        John Polstra <jdp@polstra.com>
Cc:        "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>, freebsd-current@FreeBSD.ORG
Subject:   Re: Any action on PR 10570 ? getting closer to 65K :-( 
Message-ID:  <16614.925496668@critter.freebsd.dk>
In-Reply-To: Your message of "Fri, 30 Apr 1999 11:20:19 PDT." <XFMail.990430112019.jdp@polstra.com> 

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In message <XFMail.990430112019.jdp@polstra.com>, John Polstra writes:
>Rodney W. Grimes wrote:
>>> Pierre Beyssac wrote:
>>> 
>>> > Wouldn't it be sensible to issue a warning (or panic) when
>>> > increasing the reference count reaches 0, rather than causing a
>>> > later kernel segfault? It would involve some overhead though, and
>>> > I'm not sure having 2^32 routes is currently realistic since most
>>> > machines don't even have that many bytes of RAM, but it might be
>>> > true one day...
>>> 
>>> It would be pretty hard to create 2^32 routes, given that IPv4 only
>>> has 32-bit addresses. :-) Also, if you time it I suspect you'll find
>>> that it would take a geological lifetime on a fast machine to add that
>>> many routes.
>> 
>> But some of us are playing with IPv6 and it is easy to create >2^32
>> routes in that environment.
>
>You're being totally unrealistic.  You can't create >2^32 of
>_anything_ on an i386 without running out of memory.

Well, John, you can, the newer ones will address 2^36 bytes of memory
and even a i386 can address 2^32 bytes or 2^35 bits...

But hair splitting aside, you certainly cannot create 2^32 routes
without having other significant problems, and while I agree with
Rod that the overflow should be checked, I think it should
be done with a KASSERT() if not just with a comment.

--
Poul-Henning Kamp             FreeBSD coreteam member
phk@FreeBSD.ORG               "Real hackers run -current on their laptop."
FreeBSD -- It will take a long time before progress goes too far!


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