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Patrick Rudolph 1ab8ad66d4 drivers/efi: Add EFI variable store option support
Add a driver to read and write EFI variables stored in a region device.
This is particularly useful for EDK2 as payload and allows to reuse
existing EFI tools to set/get options used by the firmware.

The write implementation is fault tolerant and doesn't corrupt the
variable store. A faulting write might result in using the old value
even though a 'newer' had been completely written.

Implemented basic unit tests for header corruption, writing existing
data and append new data into the store.

Initial firmware region state:
Initially the variable store region isn't formatted. Usually this is
done in the EDK2 payload when no valid firmware volume could be found.
It might be useful to do this offline or in coreboot to have a working
option store on the first boot or when it was corrupted.

Performance improvements:
Right now the code always checks if the firmware volume header is valid.
This could be optimised by caching the test result in heap. For write
operations it would be good to cache the end of the variable store in
the heap as well, instead of walking the whole store. For read
operations caching the entire store could be considered.

Reclaiming memory:
The EFI variable store is append write only. To update an existing
variable, first a new is written to the end of the store and then the
previous is marked invalid. This only works on PNOR flash that allow to
clear set bits, but keep cleared bits state.
This mechanisms allows a fault tolerant write, but it also requires to
"clean" the variable store for time to time. This cleaning would remove
variables that have been marked "deleted".
Such cleaning mechanism in turn must be fault tolerant and thus must use
a second partition in the SPI flash as backup/working region.
For now to cleaning is done in coreboot.

Fault checking:
The driver should check if a previous write was successful and if not
mark variables as deleted on the next operation.

Tested and working:
- Enumerate all existing variables
- Read variables
- Write variables

Change-Id: I8079f71d29da5dc2db956fc68bef1486fe3906bb
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52564
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2023-04-03 21:13:54 +00:00
3rdparty Update arm-trusted-firmware submodule to upstream master 2023-03-17 13:55:14 +00:00
Documentation mb/intel/dq67sw: Add LGA1155 microATX mainboard 2023-03-31 12:10:03 +00:00
LICENSES src/mb: Update unlicensable files with the CC-PDDC SPDX ID 2022-08-13 19:25:12 +00:00
configs mainboard/protectli/vault_ehl: Add initial structure 2023-03-03 13:34:32 +00:00
payloads libpayload: strings.h: Use builtin __ffs instead of included one 2023-03-07 17:11:05 +00:00
spd spd/lp5: Add 2 Micron memory parts 2023-03-10 13:46:26 +00:00
src drivers/efi: Add EFI variable store option support 2023-04-03 21:13:54 +00:00
tests drivers/efi: Add EFI variable store option support 2023-04-03 21:13:54 +00:00
util util/crossgcc/buildgcc: Allow bootstrapping CMake with multiple threads 2023-04-03 13:22:21 +00:00
.checkpatch.conf checkpatch.conf: Ignore check for pointer comparisons to NULL 2022-09-22 15:13:35 +00:00
.clang-format
.editorconfig
.gitignore .gitignore: Add .vscode/ 2022-08-30 17:56:55 +00:00
.gitmodules Revert ".gitmodules: Fix submodule revision to v0.1 tag" 2023-01-16 05:18:27 +00:00
.gitreview
.mailmap .mailmap: Add a .mailmap file for git 2022-03-08 18:53:47 +00:00
AUTHORS arm/libgcc: Support signed 64-bit division 2022-08-13 17:20:32 +00:00
COPYING
MAINTAINERS MAINTAINERS: Add Kevin Keijzer for ASRock B75M-ITX 2023-03-13 06:19:22 +00:00
Makefile Makefile: Fix project_filelist.txt generation 2023-02-20 10:23:53 +00:00
Makefile.inc util/ifdtool: Add option to create FMAP template 2023-03-28 13:27:50 +00:00
README.md README.md: Update links 2023-01-11 11:11:32 +00:00
gnat.adc
toolchain.inc coreboot: Add support for include-what-you-use 2022-10-11 14:33:28 +00:00

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:

https://www.coreboot.org

You can contact us directly on the coreboot mailing list:

https://doc.coreboot.org/community/forums.html

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.