- Tivoization
-
Tivoization (pronounced "Teevo-ization") is a term to describe the creation of a system that incorporates software under the terms of a copyleft software license (like the GPL), but uses hardware restrictions to prevent users from running modified versions of the software on that hardware. Richard Stallman coined the term and believes this practice denies users some of the freedom that the GNU General Public License (GNU GPL) was designed to protect.[1] The term came about in reference to TiVo's use of GNU GPL licensed software on the TiVo brand digital video recorders (DVR) which actively blocks users from running modified software on its hardware by design.[2][3]
Contents
Overview
TiVo's software incorporates the Linux kernel and GNU software, both of which are licensed under version 2 of the GNU General Public License (GPLv2). GPLv2 requires distributors to make the corresponding source code available to each person who receives the software. The goal of this requirement is to allow users of GPL'd software to modify the software to better suit their purposes.[4]
However, Stallman believes TiVo circumvented this goal by making their products run programs only if the program's digital signature matches those authorized by the manufacturer of the TiVo.[5] So while TiVo has complied with the GPL v2 requirement to release the source code for others to modify, any modified software will not run on TiVo's hardware.
On the other hand, Linus Torvalds, the original author of the Linux kernel, has argued that it is appropriate for TiVo to use digital signatures to limit what software may run on the systems that they sell. Torvalds has stated that he believes the use of private digital signatures on software is a beneficial security tool. Torvalds also believes that software licenses should attempt to control only software, not the hardware on which it runs. So, as long as one has access to the software, and can modify it to run on some other hardware, Torvalds believes there is nothing unethical about using digital signatures to prevent running modified copies of Linux.[6] Other Linux developers, including Alan Cox,[7] have expressed divergent opinions.
Stallman and the Free Software Foundation have attempted to respond to some of these concerns. They have stated that their goal is for GPLv3 to allow private digital signatures for security purposes, but to still prevent Tivoization.
Response
In 2006, Free Software Foundation (FSF) decided to combat TiVo's technical system of blocking users from running modified software. The practice was tackled by creating a new version of the GNU General Public License (GPL v3) prohibiting this activity.[8] The operating system kernel included in the TiVo is distributed under the terms of the GPL, and the FSF's goal is to ensure that all recipients of software licensed under the new GPL are not restricted by hardware constraints on the modification of distributed software. This new license provision was acknowledged by TiVo in its April 2007 SEC filing: "we may be unable to incorporate future enhancements to the GNU/Linux operating system into our software, which could adversely affect our business".[9] Regardless, the Linux kernel has not been changed to use GPL v3.
GPLv3
One of the goals of GPL Version 3 is to prevent "Tivoization". According to Eben Moglen, "the licence should prohibit technical means of evasion of its rules, with the same clarity that it prohibits legal evasion of its rules."[10]
Draft 2 of GPLv3 attempted to clarify this.[11] However, some Linux kernel developers were still concerned that draft 2 GPLv3 may still prohibit beneficial uses of digital signatures.[12]
In the third and fourth discussion drafts of GPLv3, released March 28, 2007 and May 31, 2007 respectively, the anti-tivoization clause was limited so as not to apply when the software is distributed to a business.[13] Thus, medical devices and voting machines would not be covered. The final, official GPLv3 was published on June 29, 2007 with no major changes in respect to tivoization relative to the fourth draft.
Linus Torvalds said he was "pretty pleased" with the new draft's stance on DRM.[14] However, he still does not support relicensing the Linux kernel under GPLv3:
“ [Stallman] calls it "tivoization", but that's a word he has made up, and a term I find offensive, so I don't choose to use it. It's offensive because Tivo never did anything wrong, and the FSF even acknowledged that. The fact that they do their hardware and have some DRM issues with the content producers and thus want to protect the integrity of that hardware. The kernel license covers the *kernel*. It does not cover boot loaders and hardware, and as far as I'm concerned, people who make their own hardware can design them any which way they want. Whether that means "booting only a specific kernel" or "sharks with lasers", I don't care.
” —Linus Torvalds[15]
In any case, changing the license of the Linux kernel would likely be infeasible due to its very large number of copyright holders. Unlike most GPL software, the kernel is licensed only under GPLv2 without the wording "or, at your option, any later version", therefore the agreement of all copyright holders would be required to relicense under a new version.[16]
Some other projects widely used in Tivoized embedded systems, such as Busybox, have also declined to move to GPLv3.[17]
References
- ^ [Info-gplv3] “GPLv3 Update #2” by John Sullivan, FSF on 2006-02-08
- ^ http://www.gnu.org/licenses/gpl-faq.html#Tivoization GNU.org Frequently Asked Questions about the GNU Licenses
- ^ http://www.gnu.org/licenses/quick-guide-gplv3.html A Quick Guide to GPLv3
- ^ "The Free Software Definition". http://www.gnu.org/philosophy/free-sw.html. "...The freedom to study how the program works, and adapt it to your needs..."
- ^ “Using large disks with TiVo” at www.gratisoft.us
- ^ fa.linux.kernel: Linus Torvalds: Flame Linus to a crisp! on 2003-04-24
- ^ “UK Linux guru backs GPL 3” on news.zdnet.co.uk on 2006-01-31
- ^ "Richard Stallman explains the new GPL provisions to block "tivoisation"". http://fsfeurope.org/projects/gplv3/brussels-rms-transcript#tivoisation.
- ^ "InformationWeek: TiVo Warns Investors New Open Source License Could Hurt Business". http://www.informationweek.com/industries/showArticle.jhtml?articleID=199900263.
- ^ "Eben Moglen, speaking about GPLv3 in Barcelona". http://www.fsfeurope.org/projects/gplv3/barcelona-moglen-transcript.en.html#drm.
- ^ Opinion on Digital Restrictions Management — GPLv3
- ^ linux.kernel: “GPLv3 Position Statement” by James Bottomley on 2006-09-22
- ^ "GPLv3 FAQ, with explanation of Section 6's limits". http://gplv3.fsf.org/dd3-faq.
- ^ "Torvalds 'pretty pleased' about new GPL 3 draft". CNet news.com. http://news.com.com/2061-10795_3-6171300.html.
- ^ Linus Torvalds. "Re: Dual-Licensing Linux Kernel with GPL V2 and GPL V3", Message to the Linux Kernel Mailing List dated Wed, 13 Jun 2007 14:33:07 -0700 (PDT)
- ^ http://blogs.fsfe.org/ciaran/?p=58
- ^ "http://lwn.net/Articles/202106/". LWN. http://lwn.net/Articles/202106/.
See also
External links
- Free Software Foundation definition of "Tivoization"
- An Introduction to Tivoization by The Linux Information Project (LINFO)
- Stallman, Torvalds, Moglen share views on DRM and GPLv3 - by Shashank Sharma August 09, 2006, from Newsforge
- TiVo's GPL-required modifications to the Linux kernel, glibc, and other software
- Richard Stallman's explanations of "tivoisation":
- Eben Moglen's explanations:
- Ciarán O'Riordan's explanations:
- "Using a hypervisor to reconcile GPL and proprietary embedded code" article with a focus on Tivoization
Categories:- Free software culture and documents
- Technology neologisms
Wikimedia Foundation. 2010.
