913a47a322
Over the last couple of years we have continuously added more and more CBMEM init hooks related to different independent components. One disadvantage of the API is that it can not model any dependencies between the different hooks, and their order is essentially undefined (based on link order). For most hooks this is not a problem, and in fact it's probably not a bad thing to discourage implicit dependencies between unrelated components like this... but one resource the components obviously all share is CBMEM, and since many CBMEM init hooks are used to create new CBMEM areas, the arbitrary order means that the order of these areas becomes unpredictable. Generally code using CBMEM should not care where exactly an area is allocated, but one exception is the persistent CBMEM console which relies (on a best effort basis) on always getting allocated at the same address on every boot. This is, technically, a hack, but it's a pretty harmless hack that has served us reasonably well so far and would be difficult to realize in a more robust way (without adding a lot of new infrastructure). Most of the time, coreboot will allocate the same CBMEM areas in the same order with the same sizes on every boot, and this all kinda works out (and since it's only a debug console, we don't need to be afraid of the odd one-in-a-million edge case breaking it). But one reproducible difference we can have between boots is the vboot boot mode (e.g. normal vs. recovery boot), and we had just kinda gotten lucky in the past that we didn't have differences in CBMEM allocations in different boot modes. With the recent addition of the RW_MCACHE (which does not get allocated in recovery mode), this is no longer true, and as a result CBMEM consoles can no longer persist between normal and recovery modes. The somewhat kludgy but simple solution is to just create a new class of specifically "early" CBMEM init hooks that will always run before all the others. While arbitrarily partitioning hooks into "early" and "not early" without any precise definition of what these things mean may seem a bit haphazard, I think it will be good enough in practice for the very few cases where this matters and beats building anything much more complicated (FWIW Linux has been doing something similar for years with device suspend/resume ordering). Since the current use case only relates to CBMEM allocation ordering and you can only really be "first" if you allocate in romstage, the "early" hook is only available in romstage for now (could be expanded later if we find a use case for it). Signed-off-by: Julius Werner <jwerner@chromium.org> Change-Id: If2c849a89f07a87d448ec1edbad4ce404afb0746 Reviewed-on: https://review.coreboot.org/c/coreboot/+/54737 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Furquan Shaikh <furquan@google.com> |
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| .clang-format | ||
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| Makefile | ||
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| README.md | ||
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README.md
coreboot README
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.
Payloads
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.
Supported Hardware
coreboot supports a wide range of chipsets, devices, and mainboards.
For details please consult:
Build Requirements
- make
- gcc / g++
Because Linux distribution compilers tend to use lots of patches. coreboot
does lots of "unusual" things in its build system, some of which break due
to those patches, sometimes by gcc aborting, sometimes - and that's worse -
by generating broken object code.
Two options: use our toolchain (eg. make crosstools-i386) or enable the
ANY_TOOLCHAINKconfig option if you're feeling lucky (no support in this case). - iasl (for targets with ACPI support)
- pkg-config
- libssl-dev (openssl)
Optional:
- doxygen (for generating/viewing documentation)
- gdb (for better debugging facilities on some targets)
- ncurses (for
make menuconfigandmake nconfig) - flex and bison (for regenerating parsers)
Building coreboot
Please consult https://www.coreboot.org/Build_HOWTO for details.
Testing coreboot Without Modifying Your Hardware
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.
Website and Mailing List
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
Copyright and License
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.