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+OpenSBI Platform Firmwares
+==========================
+
+OpenSBI provides firmware builds for specific platforms. Different types of
+firmwares are supported to deal with the differences between different platforms
+early boot stage. All firmwares will execute the same initialization procedure
+of the platform hardware according to the platform specific code as well as
+OpenSBI generic library code. The supported firmwares type will differ in how
+the arguments passed by the platform early boot stage are handled, as well as
+how the boot stage following the firmware will be handled and executed.
+
+OpenSBI currently supports three different types of firmwares.
+
+Firmware with Dynamic Information (*FW_DYNAMIC*)
+------------------------------------------------
+
+The *FW_DYNAMIC* firmware gets information about the next booting stage entry,
+e.g. a bootloader or an OS kernel, from previous booting stage at runtime.
+
+A *FW_DYNAMIC* firmware is particularly useful when the booting stage executed
+prior to OpenSBI firmware is capable of loading both the OpenSBI firmware
+and the booting stage binary to follow OpenSBI firmware.
+
+Firmware with Jump Address (*FW_JUMP*)
+--------------------------------------
+
+The *FW_JUMP* firmware assumes a fixed address of the next booting stage
+entry, e.g. a bootloader or an OS kernel, without directly including the
+binary code for this next stage.
+
+A *FW_JUMP* firmware is particularly useful when the booting stage executed
+prior to OpenSBI firmware is capable of loading both the OpenSBI firmware
+and the booting stage binary to follow OpenSBI firmware.
+
+Firmware with Payload (*FW_PAYLOAD*)
+------------------------------------
+
+The *FW_PAYLOAD* firmware directly includes the binary code for the booting
+stage to follow OpenSBI firmware execution. Typically, this payload will be a
+bootloader or an OS kernel.
+
+A *FW_PAYLOAD* firmware is particularly useful when the booting stage executed
+prior to OpenSBI firmware is not capable of loading both OpenSBI firmware and
+the booting stage to follow OpenSBI firmware.
+
+A *FW_PAYLOAD* firmware is also useful for cases where the booting stage prior
+to OpenSBI firmware does not pass a *flattened device tree (FDT file)*. In such
+case, a *FW_PAYLOAD* firmware allows embedding a flattened device tree in the
+.text section of the final firmware.
+
+Firmware Configuration and Compilation
+--------------------------------------
+
+All firmware types support the following common compile time configuration
+parameters:
+
+* **FW_TEXT_ADDR** - Defines the execution address of the OpenSBI firmware.
+  This configuration parameter is mandatory.
+* **FW_FDT_PATH** - Path to an external flattened device tree binary file to
+  be embedded in the *.rodata* section of the final firmware. If this option
+  is not provided then the firmware will expect the FDT to be passed as an
+  argument by the prior booting stage.
+* **FW_FDT_PADDING** - Optional zero bytes padding to the embedded flattened
+  device tree binary file specified by **FW_FDT_PATH** option.
+
+Additionally, each firmware type as a set of type specific configuration
+parameters. Detailed information for each firmware type can be found in the
+following documents.
+
+* *[FW_DYNAMIC]*: The *Firmware with Dynamic Information (FW_DYNAMIC)* is
+  described in more details in the file *fw_dynamic.md*.
+* *[FW_JUMP]*: The *Firmware with Jump Address (FW_JUMP)* is described in more
+  details in the file *fw_jump.md*.
+* *[FW_PAYLOAD]*: The *Firmware with Payload (FW_PAYLOAD)* is described in more
+  details in the file *fw_payload.md*.
+
+[FW_DYNAMIC]: fw_dynamic.md
+[FW_JUMP]: fw_jump.md
+[FW_PAYLOAD]: fw_payload.md
+
+Providing different payloads to OpenSBI Firmware
+------------------------------------------------
+OpenSBI firmware can accept various payloads using a compile time option.
+Typically, these payloads refer to the next stage boot loader (e.g. U-Boot)
+or operating system kernel images (e.g. Linux). By default, OpenSBI
+automatically provides a test payload if no specific payload is specified
+at compile time.
+
+To specify a payload at compile time, the make variable _FW_PAYLOAD_PATH_ is
+used.
+```
+make PLATFORM=<platform_subdir> FW_PAYLOAD_PATH=<payload path>
+```
+The instructions to build each payload is different and the details can
+be found in the
+*docs/firmware/payload_<payload_name>.md* files.
+
+Options for OpenSBI Firmware behaviors
+--------------------------------------
+An optional compile time flag FW_OPTIONS can be used to control the OpenSBI
+firmware run-time behaviors.
+
+```
+make PLATFORM=<platform_subdir> FW_OPTIONS=<options>
+```
+
+FW_OPTIONS is a bitwise or'ed value of various options, eg: *FW_OPTIONS=0x1*
+stands for disabling boot prints from the OpenSBI library.
+
+For all supported options, please check "enum sbi_scratch_options" in the
+*include/sbi/sbi_scratch.h* header file.