1# ABI data consumption 2 3This text describes the ABI coreboot presents to downstream users. Such 4users are payloads and/or operating systems. Therefore, this text serves 5at what can be relied on for downstream consumption. Anything not explicitly 6listed as consumable is subject to change without notice. 7 8## Background and Usage 9 10coreboot passes information to downstream users using coreboot tables. These 11table definitions can be found in 12`./src/commonlib/include/commonlib/coreboot_tables.h` and 13`./payloads/libpayload/include/coreboot_tables.h` respectively within coreboot 14and libpayload. One of the most vital and important pieces of information 15found within these tables is the memory map of the system indicating 16available and reserved memory. 17 18In 2009 cbmem was added to coreboot. The "CBMEM high table memory manager" 19serves a way for coreboot to bookkeep its own internal data. While some 20of this data may be exposed through the coreboot tables the data structures 21used to manage the data within the cbmem area is subject to change. 22 23Provided the above, if one needs a piece of data exposed to the OS 24or payload it should reside within the coreboot tables. If it isn't there 25then a code change will be required to add it to the coreboot tables. 26