Aaron Durbin (adurbin@google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9194
-gerrit
commit e88ffe35c11c44190bbbd972a469d1586e23e4b0 Author: Aaron Durbin adurbin@chromium.org Date: Wed Apr 1 09:27:44 2015 -0500
documentation: define downstream data consumption rules
It's important to document what data is available for downstream consumption by the OS and payloads. Provide details/directions on what is available.
Change-Id: Icafb6e9f59462ad19cf6a641046c6efc36f138f0 Signed-off-by: Aaron Durbin adurbin@chromium.org --- documentation/abi-data-consumption.txt | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/documentation/abi-data-consumption.txt b/documentation/abi-data-consumption.txt new file mode 100644 index 0000000..81442e7 --- /dev/null +++ b/documentation/abi-data-consumption.txt @@ -0,0 +1,22 @@ +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.