xref: /src/doc/roadmaps/licensing

$NetBSD: licensing,v 1.3 2026/01/31 12:35:12 nia Exp $

NetBSD Licensing
================

In an ideal world, the entire of NetBSD should be available under
simple permissive software licenses. The 2-clause BSD license is
recommended for new contributions.

Background: GPL in base
-----------------------

In the 1990s, the BSD developers at CSRG realized their toolchain was
falling behind alternatives. One of the reasons for this was Sun
choosing to lock their compiler behind a paywall - as a result, Sun's
users went out in search of freeware alternatives. They found GNU's GCC,
and immediately formed a new community around improving it.
Eventually, various GNU tools found their way into BSD.

We would like to eliminate the use of the GNU General Public License
in the base system. This provides a number of advantages: less worrying
about license compatibility, easier sharing of code between NetBSD
components, less likelihood of being sued for redistributing NetBSD
binaries, less legalese and need for lawyers to interpret it,
and an overall reduction in GNU info pages.

As a general rule, most GPL code in NetBSD provides programs that
are "nice to have", but not fully essential for a working system,
so redistributors have an option to remove or replace them.

For example, some NetBSD ports can be built using Clang as the
toolchain instead of GCC (see mk.conf(5), HAVE_LLVM).

GPL codes lives under the following directories to ensure clean
separation:

* src/external/gpl2
* src/external/gpl3
* src/sys/external/gpl2

Background: Advertising clause
------------------------------

At some point, Berkeley added the following clause to their license
for the free parts of BSD UNIX:

 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by [copyright holder].

With time, this clause came to be seen as onerous: there is already
a requirement to credit copyright holders in the documentation of
redistributions, and it's very difficult to enforce. At various points,
distributing NetBSD required including hundreds of "This product
includes software developed [...]" statements. It also makes it more
complicated to include NetBSD code in projects under other licenses.

Berkeley removed the advertising clause in 1999, and clarified their
stance against including it in 2012. However, there are lots of
instances where it has been copy and pasted by other people and
organizations. Therefore, its removal from NetBSD is mostly a social
challenge.

Technical priorities
--------------------

The directory under external/gpl2 contains several programs that
could be replaced. Most of them are quite old versions now, chosen
to avoid GPLv3:

* diffutils - Replaced with FreeBSD-derived diff(1). MKBSDDIFF is now
  the default.
* grep - Could be replaced with FreeBSD grep(1). Someone needs to
  compare the performance. Other grep implementations in C likely
  exist. A MKBSDGREP option exists, but the copy is probably old.
* rcs - Supposedly OpenBSD developed a compatible replacement.
* xcvs - Priority for removal as we transition away from CVS.
* groff - Mostly replaced by mandoc(1), although some non-manual use
  cases (e.g. distrib/notes) continue to rely on groff. Optional -
  a MKGROFF option exists. Such files could also be converted to
  plain text.
* send-pr - Part of our infrastructure, but basically optional -
  alternatives like the gnats web interface exist.
* gawk - Needed only by other GNU software?
* gmake - Needed only by other GNU software.
* texinfo - Needed only by other GNU software.

The directory under sys/external/gpl2 mainly contains device tree
sources, providing platform definition files for embedded system
boards. Removing this would break a lot of platforms.

The directory under external/gpl3 only contains toolchain-relevant
files, and can be mostly avoided with HAVE_LLVM=yes and elftoolchain.

Social and legal tasks
----------------------

A list of advertising clauses that still apply can be found in:

	src/distrib/notes/common/legal.common

This file should be kept in sync as copyright holders are contacted.

There are several high-priority targets for the removal of the
advertising clause:

* Lawrence Berkeley Laboratory advertising clauses are very widespread.
  It is unclear whether Berkeley granted permission to remove such
  clauses (FreeBSD apparently think so). Berkeley should be contacted
  for clarification.
* Harvard University 4-clauses licenses are widespread, and it's
  possible someone knows an insider who could accelerate the process
  of getting permission to fix them.
* Wasabi Systems copyrights are very widespread in NetBSD. They were
  "the NetBSD company" of their time. It is unclear who currently owns
  Wasabi Systems' intellectual property. Someone should figure this out,
  or we should use Foundation funds to acquire it.
* 4-clause BSD licenses are also found in the tree belonging to
  Cisco (primarily in SCTP code). It's also possible someone knows an
  insider who could accelerate the process.

Otherwise, the social and legal tasks mostly involve trying to find
old contributors' current email addresses, and asking them for
permission to relicense. This strategy has been somewhat successful,
and should be completed before doing so is no longer possible.