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Diffstat (limited to 'roms/opensbi/docs/firmware/fw_dynamic.md')
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diff --git a/roms/opensbi/docs/firmware/fw_dynamic.md b/roms/opensbi/docs/firmware/fw_dynamic.md new file mode 100644 index 000000000..01f43f9f4 --- /dev/null +++ b/roms/opensbi/docs/firmware/fw_dynamic.md @@ -0,0 +1,35 @@ +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 it's address to *FW_DYNAMIC* +via *a2* register of RISC-V CPU. + +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 *config.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 requires any platform specific configuration +parameters because all required information is passed by previous booting stage +at runtime via *struct fw_dynamic_info*. |