| OpenSBI Firmware with Dynamic Information (FW_DYNAMIC) |
| ====================================================== |
| |
| OpenSBI **firmware with dynamic info (FW_DYNAMIC)** is a firmware which gets |
| information about next booting stage (e.g. a bootloader or an OS) and runtime |
| OpenSBI library options from previous booting stage. |
| |
| The previous booting stage will pass information to *FW_DYNAMIC* by creating |
| *struct fw_dynamic_info* in memory and passing its address to *FW_DYNAMIC* |
| via *a2* register of RISC-V CPU. The address must be aligned to 8 bytes on |
| RV64 and 4 bytes on RV32. |
| |
| 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. |
| |
| *FW_DYNAMIC* Compilation |
| ------------------------ |
| |
| A platform can enable *FW_DYNAMIC* firmware using any of the following methods. |
| |
| 1. Specifying `FW_DYNAMIC=y` on the top level `make` command line. |
| 2. Specifying `FW_DYNAMIC=y` in the target platform *objects.mk* configuration |
| file. |
| |
| The compiled *FW_DYNAMIC* firmware ELF file is named *fw_dynamic.elf*. It's |
| expanded image file is *fw_dynamic.bin*. Both files are created in the platform |
| specific build directory under the *build/platform/<platform_subdir>/firmware* |
| directory. |
| |
| *FW_DYNAMIC* Firmware Configuration Options |
| ------------------------------------------- |
| |
| The *FW_DYNAMIC* firmware does not require any platform specific configuration |
| parameters because all required information is passed by previous booting stage |
| at runtime via *struct fw_dynamic_info*. |
