It is distributed under the terms of the BSD 2-clause license ("Simplified BSD License" or "FreeBSD License", SPDX: BSD-2-Clause). A copy of this license with OpenSBI copyright can be found in the file COPYING.BSD.
This enables machine processing of license information based on the SPDX License Identifiers that are available on the SPDX web site.
OpenSBI source code also contains code reused from other projects as listed below. The original license text of these projects is included in the source files where the reused code is present.
The goal of the OpenSBI project is to provide an open-source reference implementation of the RISC-V SBI specifications for platform-specific firmwares executing in M-mode (case 1 mentioned above). An OpenSBI implementation can be easily extended by RISC-V platform and system-on-chip vendors to fit a particular hardware configuration.
The main component of OpenSBI is provided in the form of a platform-independent static library libsbi.a implementing the SBI interface. A firmware or bootloader implementation can link against this library to ensure conformance with the SBI interface specifications. libsbi.a also defines an interface for integrating with platform-specific operations provided by the platform firmware implementation (e.g. console access functions, inter-processor interrupt control, etc).