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33ec85c9ab
This patch adds documentation for fw_jump and fw_payload firmware blobs. Signed-off-by: Anup Patel <anup.patel@wdc.com>
51 lines
No EOL
1.9 KiB
Markdown
51 lines
No EOL
1.9 KiB
Markdown
OpenSBI Firmware with Payload (FW_PAYLOAD)
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==========================================
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The **OpenSBI firmware with Payload (FW_PAYLOAD)** is a
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firmware which includes next booting stage binary (i.e.
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bootloader/kernel) as payload in the OpenSBI firmware binary.
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This **FW_PAYLOAD** firmware is particularly useful when
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booting stage prior to OpenSBI firmware is not capable of
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loading OpenSBI firmware and booting stage after OpenSBI
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firmware separately.
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It is also possible that booting stage prior to OpenSBI
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firmware does not pass **flattened device tree (FDT)**. In
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this case, we have provision to embed FDT in .text section
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of **FW_PAYLOAD** firmware.
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How to Enable?
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--------------
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The **FW_PAYLOAD** firmware can be enabled by any of the
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following methods:
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1. Passing `FW_PAYLOAD=y` command-line parameter to
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top-level `make`
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2. Setting `FW_PAYLOAD=y` in platform `config.mk`
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Config Options
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--------------
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We need more config details for **FW_PAYLOAD** firmware to
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work correctly. These config details can be passed as paramter
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to top-level `make` or can be set in platform `config.mk`.
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Following are the config options for **FW_PAYLOAD** firmware:
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* **FW_PAYLOAD_OFFSET** - Offset from FW_TEXT_BASE where next
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booting stage binary will be linked to **FW_PAYLOAD** firmware.
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This is a mandatory config option and will result in compile
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error if not provided.
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* **FW_PAYLOAD_PATH** - Path to the next booting stage binary.
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If this option is not provided then **`while (1)`** is taken as
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payload.
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* **FW_PAYLOAD_FDT_PATH** - Path to the FDT binary to be embedded
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in .text section of **FW_PAYLOAD** firmware. If this option is
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not provided then firmware will expect FDT to be passed by prior
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booting stage.
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* **FW_PAYLOAD_FDT_ADDR** - Address where FDT passed by prior
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booting stage (or embedded FDT) will be placed before passing
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to next booting stage. If this option is not provided then
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firmware will pass zero as FDT address to next booting stage. |