Upsilon is a copyleft hardware project, which brings its own difficulties.
Upsilon is dual-licensed in many locations.

The files under `firmware/` are disjunctive dual-licensed under the CERN-OHL-S
v2.0 (or any later version), or the GNU GPL v3.0 (or any later version).

The files under `buildroot/` and `opensbi/` are licensed under a BSD
2-clause license.

The files under `doc/` are disjunctively dual-licensed under the CC BY-SA 4.0,
or the GNU GPL v3.0 (or any later version).

The files under `software/` are disjunctively dual-licensed under the
CERN-OHL-S v2.0 (or any later version), or the GNU GPL v3.0 (or any later
version).

All license files under `copying/` (except this one) are licensed according
to the text of the license.

Any other file is licensed under the GNU GPL v3.0 (or any later version).

Some files contain additional licenses. You must comply with the terms of
both the license in a file and the licenses specified here.