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James Gutbub
c5a516be99
Performed some spell checking on the source/*.rst files in most places as needed Signed-off-by: James Gutbub <james.gutbub@intel.com>
84 lines
2.7 KiB
ReStructuredText
Executable File
84 lines
2.7 KiB
ReStructuredText
Executable File
.. _build-process:
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Build Process
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--------------
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|SPN| build process is implemented in top level build script ``BuildLoader.py``. The following diagram illustrates main steps:
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.. graphviz:: /images/build_steps.dot
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The generated files are located in ``Build/`` directory.
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The |SPN| image, configuration data, and (generated) helper scripts, are located in ``Outputs/`` directory.
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.. Note:: To assist debugging, the build process also generates ``SlimBootloader.txt`` file which contains flash layout details for each component in |SPN| image.
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.. _boot-flow:
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Boot Flow
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-------------
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|SPN| uses a linear staged boot flow to initialize platform and launch OS. It consists of four stages:
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========= ================
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Stage Description
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========= ================
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Stage 1A Pre-memory initialization
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Stage 1B Initialize main memory
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Stage 2 Post memory initialization: initialize CPU, I/O controllers, devices etc.
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Payload Load, verify and launch OS images; or perform firmware update
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========= ================
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.. graphviz:: /images/boot_flow.dot
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.. Note:: When verified boot is enabled, each current stage verifies the next stage before transferring control to the next. If verification fails, |SPN| halts the system boot.
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.. _call-graph:
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End-to-End Call Graph
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-----------------------
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The function call graph in |SPN| code from reset vector to OS launch.
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.. image:: /images/call_graph.png
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:width: 600
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:alt: |SPN| Calling Graph
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:align: center
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Platform Initialization
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-------------------------
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In |SPN|, board initialization code is located in ``Platform/<platform_foo>`` directory. Each stage provides a 'hook point' for board specific code. To port a new board, one should implement changes in ``BoardInit()`` function for each stage under ``Platform/<platform_foo>/Library`` directory::
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VOID
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BoardInit (
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IN BOARD_INIT_PHASE InitPhase
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);
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During board initialization, |SPN| further divides the flow into multiple phases to provide a fine granularity control. These phases are defined in ``PlatformService.h``::
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typedef enum {
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PreTempRamInit = 0x10,
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PostTempRamInit = 0x20,
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PreConfigInit = 0x30,
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PostConfigInit = 0x40,
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PreMemoryInit = 0x50,
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PostMemoryInit = 0x60,
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PreTempRamExit = 0x70,
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PostTempRamExit = 0x80,
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PreSiliconInit = 0x90,
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PostSiliconInit = 0xA0,
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PrePciEnumeration = 0xB0,
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PostPciEnumeration = 0xC0,
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PrePayloadLoading = 0xD0,
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PostPayloadLoading = 0xE0,
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EndOfStages = 0xF0,
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ReadyToBoot = 0xF8,
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EndOfFirmware = 0xFF
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} BOARD_INIT_PHASE;
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