README.md 3.7 KB

RISC-V Open Source Supervisor Binary Interface (OpenSBI)

The RISC-V Supervisor Binary Interface (SBI) is a recommended interface between:

  1. A pplatform specific firmware executed in M-mode and a general purpose OS hypervisor or bootloader executed in S-mode or HS-mode.
  2. A hypervisor executed in HS-mode and a general purpose OS or bootloader executed in VS-mode

The RISC-V SBI specification is maintained as an independent project by the RISC-V Foundation in Github

OpenSBI aims to provides an open-source and extensible implementation of the RISC-V SBI specification for case 1 mentioned above. OpenSBI implementation can be easily extended by RISC-V platform or System-on-Chip vendors to fit a particular hadware configuration.

OpenSBI provides three components:

  1. libsbi.a - A generic OpenSBI static library
  2. libplatsbi.a - Platform specific OpenSBI static library, that is, libsbi.a plus platform specific hooks
  3. firmwares - Platform specific bootable firmware binaries

Building and Installing generic libsbi.a

For cross-compiling, the environment variable CROSS_COMPILE_PREFIX must be defined to specify the toolchain executable name prefix, e.g. riscv64-unknown-elf- if the gcc executable used is riscv64-unknown-elf-gcc.

To build the generic OpenSBI library libsbi.a, simply execute:

make

All compiled binaries will be placed in the build directory. To specify an alternate build directory target, run:

make O=<build_directory>

To generate files to be installed for using libsbi.a in other projects, run:

make install

This will create the install directory with all necessary include files and binary files under it. To specify an alternate installation directory, run:

make I=<install_directory> install

Building and Installing platform specific libsbi.a and firmwares

The libplatsbi.a and firmware files are only built if the PLATFORM= argument is specified on make command lines. must specify the path to one of the leaf directories under the platform directory. For example, to compile the library and firmware for QEMU generic RISC-V virt machine, should be qemu/virt.

To build libsbi, libplatsbi, and firmwares for a specific platform, run:

make PLATFORM=<platform_subdir>

or

make PLATFORM=<platform_subdir> O=<build_directory>

To install libsbi, headers, libplatsbi, and firmwares, run:

make PLATFORM=<platform_subdir> install

or

make PLATFORM=<platform_subdir> I=<install_directory> install`

In addition, platform specific make command-line options to top-level make ,such as PLATFORM_ or FW_ can also be specified. These options are described under docs/platform/.md and docs/firmware/.md.

Documentation

A more detailed documenation is under the docs directory and organized as follows.

  • docs/platform_guide.md - Guidelines for adding new platform support
  • docs/library_usage.md - Guidelines for using the static library
  • docs/platform/.md - Platform specific documentation for the platform
  • docs/firmware/.md - Platform specific documentation for the firmware

    The source code is also well documented. For source level documentation, doxygen style is used. Please refer to Doxygen manual for details on this format.