f251a6a439
The details about how the CPU multiprocessor init (MP) has migrated
from coreboot to FSP can be found in
https://doc.coreboot.org/soc/intel/mp_init/mp_init.html.
The major reason behind this migration is to support the Intel
proprietary and restricted CPU feature programming which can't be
performed if coreboot sets the BIOS_DONE or BIOS Reset CPL as part
of coreboot MP Init flow (prior to calling FSP-S). Hence, the new
flow introduced with Tiger Lake platform forced having monolithic
MP Init peformed by FSP (using coreboot MP PPI wrapper code).
The last 3-4 years of FSP doing MP Init has demonstrated ample
issues during platform bringup which is specific to UEFI MP Service
implementation and not relevant to open source coreboot. This new
flow makes the debug and validation aspect complicated where
any FSP MP Init code changes should have been validated with coreboot
MP PPI wrapper else might cause some failure, unfortunately,
the validation commitment has never been met, hence, issue debugging
is the only solution that remains in practice.
Most importantly, the restricted feature programming which demanded
closed source MP Init (for features like SGX and C6DRAM) has never
been enabled in coreboot (starting with Alder Lake, the SGX feature
has been dropped).
This patch attempts to decouple FSP-S doing MP Init from the rest
of the FSP-S silicon init and introduces 2nd MultiPhase SI init
which allows bootloader to perform the mandatory SoC programming
before FSP-S has done with PM programming (a.k.a set the reset CPL).
The core/uncore BWG suggests the minimum SoC programming before
BIOS Reset CPL is set. coreboot uses the MultiPhaseSI Init Index 2
to perform the required CPU programming before enabling the BIOS
Reset CPL.
This implementation would allow us to get rid of FSP running CPU
feature programming and additionally make several EDK2 MP service
modules optional (those are packed to create FSP-S blob).
In summary, this change would allow coreboot to utilize open source
MP init without running into FSP-S related code blocks.
Note: At present, Intel Meteor Lake FSP doesn't have support for
MultiPhase SI Init, Index 2 (submitted a FSP code changes over
chrome-internal to enable this feature to decouple MP Init from
FSP-S init).
This patch is backported from
commit
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| 3rdparty | ||
| Documentation | ||
| LICENSES | ||
| configs | ||
| payloads | ||
| spd | ||
| src | ||
| tests | ||
| util | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| .mailmap | ||
| AUTHORS | ||
| COPYING | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc | ||
| README.md | ||
| gnat.adc | ||
| toolchain.inc | ||
README.md
coreboot README
coreboot is a Free Software project aimed at replacing the proprietary firmware (BIOS/UEFI) found in most computers. coreboot performs the required hardware initialization to configure the system, then passes control to a different executable, referred to in coreboot as the payload. Most often, the primary function of the payload is to boot the operating system (OS).
With the separation of hardware initialization and later boot logic, coreboot is perfect for a wide variety of situations. It can be used for specialized applications that run directly in the firmware, running operating systems from flash, loading custom bootloaders, or implementing firmware standards, like PC BIOS services or UEFI. This flexibility allows coreboot systems to include only the features necessary in the target application, reducing the amount of code and flash space required.
Source code
All source code for coreboot is stored in git. It is downloaded with the command:
git clone https://review.coreboot.org/coreboot.git.
Code reviews are done in the project's Gerrit instance.
The code may be browsed via coreboot's Gitiles instance.
The coreboot project also maintains a mirror of the project on github. This is read-only, as coreboot does not accept github pull requests, but allows browsing and downloading the coreboot source.
Payloads
After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot.
See https://doc.coreboot.org/payloads.html for a list of some of coreboot's supported payloads.
Supported Hardware
The coreboot project supports a wide range of architectures, chipsets, devices, and mainboards. While not all of these are documented, you can find some information in the Architecture-specific documentation or the SOC-specific documentation.
For details about the specific mainboard devices that coreboot supports, please consult the Mainboard-specific documentation or the Board Status pages.
Releases
Releases are currently done by coreboot every quarter. The release archives contain the entire coreboot codebase from the time of the release, along with any external submodules. The submodules containing binaries are separated from the general release archives. All of the packages required to build the coreboot toolchains are also kept at coreboot.org in case the websites change, or those specific packages become unavailable in the future.
All releases are available on the coreboot download page.
Please note that the coreboot releases are best considered as snapshots of the codebase, and do not currently guarantee any sort of extra stability.
Build Requirements and building coreboot
The coreboot build, associated utilities and payloads require many additional tools and packages to build. The actual coreboot binary is typically built using a coreboot-controlled toolchain to provide reproducibility across various platforms. It is also possible, though not recommended, to make it directly with your system toolchain. Operating systems and distributions come with an unknown variety of system tools and utilities installed. Because of this, it isn't reasonable to list all the required packages to do a build, but the documentation lists the requirements for a few different Linux distributions.
To see the list of tools and libraries, along with a list of instructions to get started building coreboot, go to the Starting from scratch tutorial page.
That same page goes through how to use QEMU to boot the build and see the output.
Website and Mailing List
Further details on the project, as well as links to documentation and more can be found on the coreboot website:
You can contact us directly on the coreboot mailing list:
https://www.coreboot.org/Mailinglist
Copyrights and Licenses
Uncopyrightable files
There are many files in the coreboot tree that we feel are not copyrightable due to a lack of creative content.
"In order to qualify for copyright protection in the United States, a work must satisfy the originality requirement, which has two parts. The work must have “at least a modicum” of creativity, and it must be the independent creation of its author."
https://guides.lib.umich.edu/copyrightbasics/copyrightability
Similar terms apply to other locations.
These uncopyrightable files include:
- Empty files or files with only a comment explaining their existence. These may be required to exist as part of the build process but are not needed for the particular project.
- Configuration files either in binary or text form. Examples would be files such as .vbt files describing graphics configuration, spd files as binary .spd or text *spd*.hex representing memory chip configuration.
- Machine-generated files containing version numbers, dates, hash values or other "non-creative" content.
As non-creative content, these files are in the public domain by default. As such, the coreboot project excludes them from the project's general license even though they may be included in a final binary.
If there are questions or concerns about this policy, please get in touch with the coreboot project via the mailing list.
Copyrights
The copyright on coreboot is owned by quite a large number of individual developers and companies. A list of companies and individuals with known copyright claims is present at the top level of the coreboot source tree in the 'AUTHORS' file. Please check the git history of each of the source files for details.
Licenses
Because of the way coreboot began, using a significant amount of source code from the Linux kernel, it's licensed the same way as the Linux Kernel, with GNU General Public License (GPL) Version 2. Individual files are licensed under various licenses, though all are compatible with GPLv2. The resulting coreboot image is licensed under the GPL, version 2. All source files should have an SPDX license identifier at the top for clarification.
Files under coreboot/Documentation/ are licensed under CC-BY 4.0 terms. As an exception, files under Documentation/ with a history older than 2017-05-24 might be under different licenses.
Files in the coreboot/src/commonlib/bsd directory are all licensed with the BSD-3-clause license. Many are also dual-licensed GPL-2.0-only or GPL-2.0-or-later. These files are intended to be shared with libpayload or other BSD licensed projects.
The libpayload project contained in coreboot/payloads/libpayload may be licensed as BSD or GPL, depending on the code pulled in during the build process. All GPL source code should be excluded unless the Kconfig option to include it is set.
The Software Freedom Conservancy
Since 2017, coreboot has been a member of The Software Freedom Conservancy, a nonprofit organization devoted to ethical technology and driving initiatives to make technology more inclusive. The conservancy acts as coreboot's fiscal sponsor and legal advisor.