Date: Sat, 24 Dec 2011 16:28:30 -0500 From: David Schultz <das@FreeBSD.ORG> To: "Alexander V. Chernikov" <melifaro@FreeBSD.ORG> Cc: glebuis@FreeBSD.ORG, freebsd-arch@FreeBSD.ORG Subject: Re: Use of RCU (read-copy-update) Message-ID: <20111224212830.GA58693@zim.MIT.EDU> In-Reply-To: <4EF5FD0E.9050500@FreeBSD.org> References: <4EF5FD0E.9050500@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sat, Dec 24, 2011, Alexander V. Chernikov wrote: > Main problem: Idea is patended: > General worlds: > http://www.groklaw.net/articlebasic.php?story=20061028211523142 > Patents in PDF: > http://www.groklaw.net/pdf/IBM-835-Exhibit_522.pdf > http://www.groklaw.net/pdf/IBM-835-Exhibit_523.pdf > http://www.groklaw.net/pdf/IBM-835-Exhibit_524.pdf [...] > What can we do about this? > 1) Do nothing. > > 2) Check if there a way to write and implementation non-covered by those > patents > > 3) Determine exact conditions under which IBM permits using RCU? (maybe > ask IBM directly?) > > 4) Consider the possibility of buying license from IBM (if we can > redistribute code under BSD license after that) Negotiating or fighting patents is a messy business, so a technical solution may be easier. The ideas behind RCU are very old, so one way out is to implement one of the older out-of-patent ideas directly. In an expired patent, IBM called the idea "passive serialization." You can also find a lot of (hopefully unencumbered) research on "software transactional memory", which is a nice abstraction for a similar mechanism. (Most of the papers focus on how to do atomic read-write transactions; read-only transactions are much easier.) But be careful: If you independently invent an improvement that isn't covered by the older patent but is covered by RCU, that idea may still infringe.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20111224212830.GA58693>