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@@ -4,79 +4,109 @@ RISC-V Open Source Supervisor Binary Interface (OpenSBI)
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The **RISC-V Supervisor Binary Interface (SBI)** is a recommended
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interface between:
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-1. Platform specific firmware running in M-mode and
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- general-purpose-os/hypervisor/bootloader running in S-mode/HS-mode
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-2. Hypervisor runnng in HS-mode and general-purpose-os/bootloader
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- running in VS-mode
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-
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-The **RISC-V SBI specification** is maintained as independent project
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-by RISC-V Foundation on [Github](https://github.com/riscv/riscv-sbi-doc)
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-
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-The **RISC-V OpenSBI project** aims to provides an open-source and
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-extensible implementation of the **RISC-V SBI specification** for
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-point 1) mentioned above. It can be easily extended by RISC-V platform
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-or RISC-V System-on-Chip vendors.
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-
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-We can create three things using the RISC-V OpenSBI project:
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-
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-1. **libsbi.a** - Generic OpenSBI static library
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-2. **libplatsbi.a** - Platform specific OpenSBI static library
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- (It is libsbi.a plus platform specific hooks represented
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- by "platform" symbol)
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-3. **firmwares** - Platform specific firmware binaries
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-
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-How to Build?
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--------------
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-
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-For cross-compiling, the environment variable CROSS_COMPILE_PREFIX must be
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-defined to specify the toolchain executable name prefix, e.g.
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-"riscv64-unknown-elf-" for riscv64-unknown-elf-gcc.
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-
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-The libplatsbi.a and firmwares are optional and only built when
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-`PLATFORM=<platform_subdir>` parameter is specified to top-level make.
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-(**NOTE**: `<platform_subdir>` is sub-directory under platform/ directory)
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-
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-To build and install Generic OpenSBI library do the following:
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-
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-1. Build **libsbi.a**:
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-`make`
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-OR
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-`make O=<build_directory>`
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-2. Install **libsbi.a and headers**:
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-`make install`
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-OR
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-`make I=<install_directory> install`
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-
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-To build and install platform specific OpenSBI library and firmwares
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-do the following:
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-
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-1. Build **libsbi, libplatsbi, and firmwares**:
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-`make PLATFORM=<platform_subdir>`
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-OR
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-`make PLATFORM=<platform_subdir> O=<build_directory>`
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-2. Install **libsbi, headers, libplatsbi, and firmwares**:
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-`make PLATFORM=<platform_subdir> install`
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-OR
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-`make PLATFORM=<platform_subdir> I=<install_directory> install`
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-
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-In addition, we can also specify platform specific command-line
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-options to top-level make (such as `PLATFORM_<xyz>` or `FW_<abc>`)
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-which are described under `docs/platform/<platform_name>.md` OR
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-`docs/firmware/<firmware_name>.md`.
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+1. A pplatform specific firmware executed in M-mode and a general purpose
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+ OS hypervisor or bootloader executed in S-mode or HS-mode.
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+2. A hypervisor executed in HS-mode and a general purpose OS or bootloader
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+ executed in VS-mode
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+
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+The *RISC-V SBI specification* is maintained as an independent project
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+by the RISC-V Foundation in [Github](https://github.com/riscv/riscv-sbi-doc)
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+
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+OpenSBI aims to provides an open-source and extensible implementation of
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+the RISC-V SBI specification for case 1 mentioned above. OpenSBI
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+implementation can be easily extended by RISC-V platform or System-on-Chip
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+vendors to fit a particular hadware configuration.
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+
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+OpenSBI provides three components:
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+
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+1. *libsbi.a* - A generic OpenSBI static library
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+2. *libplatsbi.a* - Platform specific OpenSBI static library, that is,
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+ libsbi.a plus platform specific hooks
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+3. *firmwares* - Platform specific bootable firmware binaries
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+
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+Building and Installing generic *libsbi.a*
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+------------------------------------------
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+
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+For cross-compiling, the environment variable *CROSS_COMPILE_PREFIX* must
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+be defined to specify the toolchain executable name prefix, e.g.
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+*riscv64-unknown-elf-* if the gcc executable used is
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+*riscv64-unknown-elf-gcc*.
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+
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+To build the generic OpenSBI library *libsbi.a*, simply execute:
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+```
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+make
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+```
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+
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+All compiled binaries will be placed in the *build* directory.
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+To specify an alternate build directory target, run:
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+```
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+make O=<build_directory>
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+```
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+
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+To generate files to be installed for using *libsbi.a* in other projects,
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+run:
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+```
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+make install
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+```
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+This will create the *install* directory with all necessary include files
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+and binary files under it. To specify an alternate installation directory,
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+run:
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+```
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+make I=<install_directory> install
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+```
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+
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+Building and Installing platform specific *libsbi.a* and firmwares
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+------------------------------------------------------------------
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+
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+The libplatsbi.a and firmware files are only built if the
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+*PLATFORM=<platform path>* argument is specified on make command lines.
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+*<platform path>* must specify the path to one of the leaf directories
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+under the *platform* directory. For example, to compile the library and
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+firmware for QEMU generic RISC-V *virt* machine, *<platform path>*
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+should be *qemu/virt*.
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+
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+To build *libsbi, libplatsbi, and firmwares* for a specific platform, run:
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+```
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+make PLATFORM=<platform_subdir>
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+```
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+
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+or
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+
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+```
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+make PLATFORM=<platform_subdir> O=<build_directory>
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+```
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+
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+To install *libsbi, headers, libplatsbi, and firmwares*, run:
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+```
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+make PLATFORM=<platform_subdir> install
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+```
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+
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+or
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+
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+```
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+make PLATFORM=<platform_subdir> I=<install_directory> install`
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+```
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+
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+In addition, platform specific make command-line options to top-level make
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+,such as *PLATFORM_<xyz>* or *FW_<abc>* can also be specified. These
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+options are described under *docs/platform/<platform_name>.md* and
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+*docs/firmware/<firmware_name>.md*.
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Documentation
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-------------
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-All our documenation is under `docs` directory organized in following
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-manner:
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+A more detailed documenation is under the *docs* directory and organized
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+as follows.
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+
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+* *docs/platform_guide.md* - Guidelines for adding new platform support
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+* *docs/library_usage.md* - Guidelines for using the static library
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+* *docs/platform/<platform_name>.md* - Platform specific documentation for
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+ the platform *<platform_name>*
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+* *docs/firmware/<firmware_name>.md* - Platform specific documentation for
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+ the firmware *<firmware_name>*
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-* `docs/platform_guide.md` - Guidelines for adding new platform support
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-* `docs/library_usage.md` - Guidelines for using static library
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-* `docs/platform/<platform_name>.md` - Documentation for `<platform_name>` platform
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-* `docs/firmware/<firmware_name>.md` - Documentation for firmware `<firmware_name>`
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+The source code is also well documented. For source level documentation,
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+doxygen style is used. Please refer to [Doxygen manual]
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+(http://www.stack.nl/~dimitri/doxygen/manual.html) for details on this
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+format.
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-We also prefer source level documentation, so wherever possible we describe
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-stuff directly in the source code. This helps us maintain source and its
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-documentation at the same place. For source level documentation we strictly
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-follow Doxygen style. Please refer [Doxygen manual]
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-(http://www.stack.nl/~dimitri/doxygen/manual.html) for details.
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