Re: Patch: passive serialization

["Steven M. Bellovin" <smb%cs.columbia.edu@localhost>]

On Sun, 11 Jan 2009 21:35:55 +0000
Andrew Doran <ad%NetBSD.org@localhost> wrote:

> > I just wonder if there are ways to validate that it is really
> > patent-free.
> 
> In my opinion as a layman it is, having interpreted the patent in an
> unforgiving way, although I can give no guarantee of that. IPI based
> checkpointing may or may not be covered by the claims and
> descriptions.
> 
> Purely as a matter of record I do not advocate infringing on software
> patents but abhor and strongly discourage any infringement of
> patents, and it is with this in mind that I made the original posting
> in full and honest belief that what I have written is true: the
> technique does not infringe any other patents that I am aware of,
> because the technique is covered by an existing lapsed patent. I am
> not an expert in this field and so my interpretation of the situation
> cannot be relied on. *

As a legal note, one can never be sure of something like that.  A
patent is not the right to do something, it's the right to prevent
others from doing something.  To use the example a lawyer once
explained to me, suppose that someone the patent on the car, and you've
invented and patented the foot throttle for a car.  You can't make cars
with foot throttles without a license, because doing so would infringe
the car patent.  Similarly, if you let your patent on the foot throttle
lapse (perhaps by not paying maintenance fees), there might still be a
patent on the particular kind of linkage that someone else wants to use
to build such cars.

It's good that this patent is no longer in force, but one has to be
careful about assertions of availability of the technique.  Of course,
that's *always* true; just because you don't know of a patent doesn't
mean there isn't one.  The *only* difference here is that we know of
one patent; something you've learned about solely from the academic
literature may also be patented.  In other words, I've said nothing
relevant to this case in this note...


                --Steve Bellovin, http://www.cs.columbia.edu/~smb