FreeBSD, Clang and GCC: Copyleft vs. Community


Mike Gerwitz

A useful perspective explaining why FreeBSD is moving away from GCC in favor of Clang[0]; indeed, they are moving away from GPL-licensed software in general. While this is not a perspective that I personally agree with[1], it is one that I will respect for the project. It is worth understanding the opinions of those who disagree with you to better understand and formulate your own perspective.

But I am still a free software activist.

The goal of the FreeBSD Project is to provide a stable and fast general purpose operating system that may be used for any purpose without strings attached.[2]
As is mentioned in the aforementioned article[0], the BSD community does not hold the same opinions on what constitutes “without strings attached”—the BSD community considers the restriction on the user's right to make proprietary use of the software to be a “string”[2], whereas the free software community under RMS[3] believes that the ability to make a free program proprietary is unjust[4]:
Making a program proprietary is an exercise of power. Copyright law today grants software developers that power, so they and only they choose the rules to impose on everyone else—a relatively small number of people make the basic software decisions for all users, typically by denying their freedom. When users lack the freedoms that define free software, they can't tell what the software is doing, can't check for back doors, can't monitor possible viruses and worms, can't find out what personal information is being reported (or stop the reports, even if they do find out). If it breaks, they can't fix it; they have to wait for the developer to exercise its power to do so. If it simply isn't quite what they need, they are stuck with it. They can't help each other improve it.[4]
The Modified BSD License[5] is a GPL-compatible Free Software license—that is, software licensed under the Modified BSD license meets the requirements of the Free Software Definition[6]. The additional “string” that the BSD community is referring to is the concept of copyleft[7]—Richard Stallman's copyright hack and one of his most substantial contributions to free software and free society. To put it into the words of the FSF:
Copyleft is a general method for making a program (or other work) free, and requiring all modified and extended versions of the program to be free as well.[7]
Critics often adopt the term “viral” in place of “copyleft”[8] because of the requirement that all derivatives must contain the same copyleft terms—the derivative must itself be Free Software, perpetually (until, of course, the copyright term expires and it becomes part of the public domain, if such a thing will ever happen at this rate[9]). In the case of the Modified BSD license—being a more permissive license that is non-copyleft and thus allows proprietary derivatives—derivative works that include both BSD- and GPL-licensed code essentially consume the Modified BSD license's terms[10], which are a subset of the GPL's[11]. Of course, this is not pursuant to FreeBSD's goals[2] and so they consider this to be a bad thing: There are “strings attached”.

This is more demonstrative of the “open source” philosophy than that of “Free Software”[12] (yes, notice the bias in my capitalization of these terms).

Copyleft is important[7] because it ensures that all users will forever have the four fundamental freedoms associated with Free Software[6]. The GPL incorporates copyleft; BSD licenses do not. Consider why this is a problem: Imagine some software Foo licensed under the Modified BSD license[10]. Foo is free software; it is licensed under a free software license (Modified BSD).[5] Now consider that someone makes a fork—a derivative—of Foo, which we will call “Foobar”. Since the Modified BSD license is not copyleft[10], the author of Foobar decides that he or she does not wish to release its source code; this is perfectly compliant with the Modified BSD license, as it does not require that source code be distributed with a binary (it only requires—via its second clause[10]—that the copyright notice, list of conditions and disclaimer be provided).

The author has just taken Foo and made it proprietary.

The FreeBSD community is okay with this; the free software community is not[4]. There is a distinction between these two parties: When critics of copyleft state that they believe the GPL is “less free” than more permissive licenses such as the BSD licenses, they are taking into consideration the freedoms of developers and distributors; the GPL, on the other hand, explicirly restricts these parties' rights in order to protect the users because those parties are precisely those that seek to restrict the users' freedoms; we cannot provide such freedoms to developers and distributors without sacrificing the rights of the vulnerable users who generally do not have the skills to protect themselves from being taken advantage of.[13] Free software advocates have exclusive, unwaivering loyalty to users.

As an example of the friction between the two communities, consider a concept that has been termed “tivoization”[14]:

Tivoization means certain “appliances” (which have computers inside) contain GPL-covered software that you can't effectively change, because the appliance shuts down if it detects modified software. The usual motive for tivoization is that the software has features the manufacturer knows people will want to change, and aims to stop people from changing them. The manufacturers of these computers take advantage of the freedom that free software provides, but they don't let you do likewise.[14]
This anti-feature[15] is a type of Digital Restrictions Management (DRM)[16] that exposes a loophole in the GPL that was closed in Section 3 of the GPLv3[14], which requires that:
When you convey a covered work, you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to the covered work, and you disclaim any intention to limit operation or modification of the work as a means of enforcing, against the work's users, your or third parties' legal rights to forbid circumvention of technological measures.[11]
Unfortunately, not everyone has agreed with this move. A number of developers of the kernel Linux expressed their opposition of GPLv3[17]. In response to the aforementioned GPLv3 provision, they stated:
While we find the use of DRM by media companies in their attempts to reach into user owned devices to control content deeply disturbing, our belief in the essential freedoms of section 3 forbids us from ever accepting any licence which contains end use restrictions. The existence of DRM abuse is no excuse for curtailing freedoms.[17]
Linus Torvalds—the original author of the kernel Linux—also expressed his distaste toward the GPLv3[18]; the kernel is today still licensed under the GPLv2.

The BSD camp has similar objections[19]:

Appliance vendors in particular have the most to lose if the large body of software currently licensed under GPLv2 today migrates to the new license. They will no longer have the freedom to use GPLv3 software and restrict modification of the software installed on their hardware. High support costs ("I modified the web server on my Widget 2000 and it stopped running...") and being unable to guarantee adherence to specifications in order to gain licensing (e.g. FCC spectrum use, Cable TV and media DRM requirements) are only two of a growing list of issues for these users.[19] --Justin Gibbs, VP of The FreeBSD Foundation
My thoughts while reading the above where echoed by Gibbs further on in his statement: “[T]he stark difference between the BSD licensing philosophy and that of the Free Software Foundation are only too clear.” For the FreeBSD community, this is a very serious issue and their argument is certainly a legitimate concern on the surface. However, it is an argument that the Free Software community would do well to reject: Why would we wish to sacrifice users' freedoms for any reason, let alone these fairly absurd ones. In particular, a support contract could dictate that only unmodified software will be provided assistance and even mandate that the hardware indicate changes in software: like breaking the “void” sticker when opening a hardware component. Moreover, how frequently would such a situation actually happen relative to their entire customer base? My guess is: fairly infrequently. The second issue is a more complicated one, as I am not as familiar on such topics, but a manufacturer can still assert that the software that it provides with its devices is compliant. If the compliance process forbids any possibility of brining the software into non-compliance—that is, allowing the user to modify the software—then the hardware manufacturer can choose to not use free software (and free software advocates will subsequently reject it until standards bodies grow up).

As I mentioned at the beginning of this article: this is a view that I will respect for the project. I disagree with it, but FreeBSD is still free software and we would do well not to discriminate against it simply because someone else may decide to bastardize it and betray their users by making it proprietary or providing shackles[16]. However, provided the licensing option for your own software, you should choose the GPL.

Colophon: The title of this article is a play on RMS' “Copyright vs. Communty”[20], which is a title to a speech he frequently provides worldwide. His speech covers how copyright works against the interests of the community; here, BSD advocates aruge that copyleft[7] works against the interests of their community and their users; I figured that I would snag this title as a free software advocate before someone else opposing copyleft did.)














[13] Technically, the GPL exercises restrictions only on distributors; a developer can integrate GPL'd code into their proprietary software so long as they do not distribute it (as defined in the GPL).[11] However, developers often have to cater to distributors, since software will generally be distributed; if it is not, then it is not relevant to this discussion.