Licensing Handling For OS Builders
Note: This is not legal advice; if you want that, consult a lawyer. This section discusses purely technical measures that are available to builders. Also be aware that this system is not perfect, and may make mistakes. You should not rely on it to fulfill legal obligations.
The Chromium OS build system provides a method for automatically tracking licenses used by packages that are built & installed. This allows you to easily generate an image that only contains code that is under an FOSS license (e.g. a BSD or GPL variant). It also allows you to set even more restrictive guidelines such as only building packages that fall under BSD style licenses (thus filtering out all other licenses such as GPL), or filtering out specific licenses such as the GPL-3.
This is all done via the ACCEPT_LICENSE make.conf variable.
Note: The implication of ACCEPT_LICENSE is that you are accepting the terms of every license that ends up in the image. Be sure to review each one that is listed to verify this is OK for your needs.
The ACCEPT_LICENSE variable is a whitespace delimited list of elements. Each element takes the form of:
- an explicit license name (e.g. "GPL-2" or "BSD")
- a license group name (starts with an "@")
- a glob that means "all licenses"
Each of these elements can be prefixed with a "-" to mean you want to remove that specific element from the accepted list.
The list is incremental. That means later values add on to previous ones, so "a b -a" is equivalent to "b".
Accept all licenses except for the EULA group:
Accept only the BSD and GPL-2 license:
Accept all Free Software licenses, except for the GPL-3:
The default set of licenses that Chromium OS accepts are:
$ portageq envvar ACCEPT_LICENSE * -@EULA -@CHROMEOS
This means all licenses that the system knows about, except for ones that require explicit EULA agreements, and ones in the CHROMEOS group. In practice, this means all licenses considered Free Software (either officially by the OSI or FSF, or follow the FSF guidelines), and licenses that allow for binary redistribution (e.g. firmware for hardware devices).
Sometimes when you try building for a board, you might run into errors like:
The following license changes are necessary to proceed: #required by virtual/opengles-2-r2, required by chromeos-base/chromeos-0.0.1-r181[opengles], required by chromeos-base/chromeos (argument) >=media-libs/mali-drivers-bin-0.45-r96 Google-TOS
This is telling you that the package you're attempting to pull in (either directly, or by other packages) is using a license that has not been accepted (by virtue of being listed in the ACCEPT_LICENSE variable). You need to review this specific license, make sure you're OK with the terms of it, and then either agree to it, or find another way of building things that do not use this package.
If you do agree to the license, you can declare that intention in a couple of ways:
- update the make.conf file in your board's overlay and set ACCEPT_LICENSE in there
- update the /etc/make.conf.user file in your chroot and set ACCEPT_LICENSE in there
- `export ACCEPT_LICENSE="...some values..."` in your shell -- note that you'll have to re-export this every time you enter the chroot via `cros_sdk`
- if you're running build_packages, use the --accept_licenses flag to pass an explicit list -- note that this flag must be included every time you run build_packages