forked from ~ljy/RK3588_XEN
OpenSBI firmware with Payload (FW_PAYLOAD) is a firmware which directly
includes the binary for the booting stage to follow the 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 the OpenSBI firmware is not capable of loading both the 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 the OpenSBI firmware does not pass a flattened device tree (FDT file). In
such a case, a FW_PAYLOAD firmware allows embedding a flattened device tree
in the .text section of the final firmware.
The FW_PAYLOAD firmware can be enabled by any of the following methods:
FW_PAYLOAD=y on the top level make command line.FW_PAYLOAD=y in the target platform config.mk configurationThe compiled FW_PAYLOAD firmware ELF file is named fw_jump.elf. Its
expanded image file is fw_payload.bin. Both files are created in the
platform-specific build directory under the
build/platform//firmware directory.
A FW_PAYLOAD firmware is built according to configuration parameters and
options. These configuration parameters can be defined using either the top
level make command line or the target platform config.mk configuration
file. The parameters currently defined are as follows:
FW_PAYLOAD_OFFSET - Offset from FW_TEXT_BASE where the payload binary
will be linked in the final FW_PAYLOAD firmware binary image. This
configuration parameter is mandatory if FW_PAYLOAD_ALIGN is not defined.
Compilation errors will result from an incorrect definition of
FW_PAYLOAD_OFFSET or of FW_PAYLOAD_ALIGN, or if neither of these
parameters are defined.
FW_PAYLOAD_ALIGN - Address alignment constraint where the payload binary
will be linked after the end of the base firmware binary in the final
FW_PAYLOAD firmware binary image. This configuration parameter is mandatory
if FW_PAYLOAD_OFFSET is not defined. If both FW_PAYLOAD_OFFSET and
FW_PAYLOAD_ALIGN are defined, FW_PAYLOAD_OFFSET is used and
FW_PAYLOAD_ALIGN is ignored.
FW_PAYLOAD_PATH - Path to the image file of the next booting stage
binary. If this option is not provided then a simple test payload is
automatically generated and used as a payload. This test payload executes
an infinite while (1) loop after printing a message on the platform console.
FW_PAYLOAD_FDT_PATH - Path to an external flattened device tree binary
file to be embedded in the .text 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_PAYLOAD_FDT_ADDR - Address where the FDT passed by the prior booting
stage or specified by the FW_PAYLOAD_FDT_PATH parameter and embedded in
the .text section will be placed before executing the next booting stage,
that is, the payload firmware. If this option is not provided, then the
firmware will pass the FDT address passed by the previous booting stage
to the next booting stage.
The qemu/virt platforms illustrate how to configure and use a FW_PAYLOAD
firmware. Detailed information regarding these platforms can be found in the
platform documentation files.