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8e9966c1a7
Corrected the typos of some documents in the 'docs' folder. Signed-off-by: zhangdongdong <zhangdongdong@eswincomputing.com> Reviewed-by: Anup Patel <anup@brainfault.org>
36 lines
1.6 KiB
Markdown
36 lines
1.6 KiB
Markdown
OpenSBI Firmware with Dynamic Information (FW_DYNAMIC)
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======================================================
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OpenSBI **firmware with dynamic info (FW_DYNAMIC)** is a firmware which gets
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information about next booting stage (e.g. a bootloader or an OS) and runtime
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OpenSBI library options from previous booting stage.
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The previous booting stage will pass information to *FW_DYNAMIC* by creating
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*struct fw_dynamic_info* in memory and passing its address to *FW_DYNAMIC*
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via *a2* register of RISC-V CPU. The address must be aligned to 8 bytes on
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RV64 and 4 bytes on RV32.
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A *FW_DYNAMIC* firmware is particularly useful when the booting stage executed
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prior to OpenSBI firmware is capable of loading both the OpenSBI firmware and
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the booting stage binary to follow OpenSBI firmware.
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*FW_DYNAMIC* Compilation
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------------------------
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A platform can enable *FW_DYNAMIC* firmware using any of the following methods.
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1. Specifying `FW_DYNAMIC=y` on the top level `make` command line.
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2. Specifying `FW_DYNAMIC=y` in the target platform *objects.mk* configuration
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file.
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The compiled *FW_DYNAMIC* firmware ELF file is named *fw_dynamic.elf*. It's
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expanded image file is *fw_dynamic.bin*. Both files are created in the platform
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specific build directory under the *build/platform/<platform_subdir>/firmware*
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directory.
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*FW_DYNAMIC* Firmware Configuration Options
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-------------------------------------------
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The *FW_DYNAMIC* firmware does not require any platform specific configuration
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parameters because all required information is passed by previous booting stage
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at runtime via *struct fw_dynamic_info*.
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