| commit | 81dc20e744aa1762c17dcf5aac5c37643d62a983 | [log] [tgz] |
|---|---|---|
| author | Julius Werner <jwerner@chromium.org> | Thu Oct 15 17:37:57 2020 -0700 |
| committer | Patrick Georgi <pgeorgi@google.com> | Wed Mar 17 08:10:00 2021 +0000 |
| tree | 1605652d540d384b6ea5b4ca585cba25d1a720d8 | |
| parent | 2e973942bc34ff2d7b110ba35bf3cda987838907 [diff] |
cbfs: Move stage header into a CBFS attribute The CBFS stage header is part of the file data (not the header) from CBFS's point of view, which is problematic for verification: in pre-RAM environments, there's usually not enough scratch space in CBFS_CACHE to load the full stage into memory, so it must be directly loaded into its final destination. However, that destination is decided from reading the stage header. There's no way we can verify the stage header without loading the whole file and we can't load the file without trusting the information in the stage header. To solve this problem, this patch changes the CBFS stage format to move the stage header out of the file contents and into a separate CBFS attribute. Attributes are part of the metadata, so they have already been verified before the file is loaded. Since CBFS stages are generally only meant to be used by coreboot itself and the coreboot build system builds cbfstool and all stages together in one go, maintaining backwards-compatibility should not be necessary. An older version of coreboot will build the old version of cbfstool and a newer version of coreboot will build the new version of cbfstool before using it to add stages to the final image, thus cbfstool and coreboot's stage loader should stay in sync. This only causes problems when someone stashes away a copy of cbfstool somewhere and later uses it to try to extract stages from a coreboot image built from a different revision... a debugging use-case that is hopefully rare enough that affected users can manually deal with finding a matching version of cbfstool. The SELF (payload) format, on the other hand, is designed to be used for binaries outside of coreboot that may use independent build systems and are more likely to be added with a potentially stale copy of cbfstool, so it would be more problematic to make a similar change for SELFs. It is not necessary for verification either, since they're usually only used in post-RAM environments and selfload() already maps SELFs to CBFS_CACHE before loading them to their final destination anyway (so they can be hashed at that time). Signed-off-by: Julius Werner <jwerner@chromium.org> Change-Id: I8471ad7494b07599e24e82b81e507fcafbad808a Reviewed-on: https://review.coreboot.org/c/coreboot/+/46484 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org>
coreboot is a Free Software project aimed at replacing the proprietary BIOS (firmware) found in most computers. coreboot performs a little bit of hardware initialization and then executes additional boot logic, called a payload.
With the separation of hardware initialization and later boot logic, coreboot can scale from specialized applications that run directly firmware, run operating systems in flash, load custom bootloaders, or implement firmware standards, like PC BIOS services or UEFI. This allows for systems to only include the features necessary in the target application, reducing the amount of code and flash space required.
coreboot was formerly known as LinuxBIOS.
After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot.
See https://www.coreboot.org/Payloads for a list of supported payloads.
coreboot supports a wide range of chipsets, devices, and mainboards.
For details please consult:
ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case).Optional:
make menuconfig and make nconfig)Please consult https://www.coreboot.org/Build_HOWTO for details.
If you want to test coreboot without any risks before you really decide to use it on your hardware, you can use the QEMU system emulator to run coreboot virtually in QEMU.
Please see https://www.coreboot.org/QEMU for details.
Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the coreboot website:
You can contact us directly on the coreboot mailing list:
https://www.coreboot.org/Mailinglist
The copyright on coreboot is owned by quite a large number of individual developers and companies. Please check the individual source files for details.
coreboot is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details.
This makes the resulting coreboot images licensed under the GPL, version 2.