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