26 lines
1.2 KiB
Markdown
26 lines
1.2 KiB
Markdown
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# ABI data consumption
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This text describes the ABI coreboot presents to downstream users. Such
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users are payloads and/or operating systems. Therefore, this text serves
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at what can be relied on for downstream consumption. Anything not explicitly
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listed as consumable is subject to change without notice.
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## Background and Usage
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coreboot passes information to downstream users using coreboot tables. These
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table definitions can be found in
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`./src/commonlib/include/commonlib/coreboot_tables.h` and
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`./payloads/libpayload/include/coreboot_tables.h` respectively within coreboot
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and libpayload. One of the most vital and important pieces of information
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found within these tables is the memory map of the system indicating
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available and reserved memory.
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In 2009 cbmem was added to coreboot. The "CBMEM high table memory manager"
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serves a way for coreboot to bookkeep its own internal data. While some
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of this data may be exposed through the coreboot tables the data structures
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used to manage the data within the cbmem area is subject to change.
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Provided the above, if one needs a piece of data exposed to the OS
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or payload it should reside within the coreboot tables. If it isn't there
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then a code change will be required to add it to the coreboot tables.
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