117e436115
We currently have two competing mechanisms to limit the placement of resources: 1. the explicit `.limit` field of a resource, and 2. the IORESOURCE_ABOVE_4G flag. This makes the resource allocator unnecessarily complex. Ideally, we would always reduce the `.limit` field if we want to "pin" a specific resource below 4G. However, as that's not done across the tree yet, we will use the _absence_ of the IORESOURCE_ABOVE_4G flag as a hint to implicitly lower the `limit` of a resource. In this patch, this is done inside the effective_limit() function that hides the flag from the rest of the allocator. To automatically place resources above 4G if their limit allows it, we have to allocate from top down. Hence, we disable the prompt for RESOURCE_ALLOCATION_TOP_DOWN if resources above 4G are requested. One implication of the changes is that we act differently when a cold-plugged device reports a prefetchable resource with 32-bit limit. Before this change, we would fail to allocate the resource. After this change, it forces everything on the same root port below the 4G line. A possible solution to get completely rid of the IORESOURCE_ABOVE_4G flag would be rules to place resources of certain devices below 4G. For instance, the primary VGA device and storage and HID devices could be made available to a payload that can only address 32 bits. For now, effective_limit() provides us enough abstraction as if the `limit` would be the only variable to consider. With this, we get rid of all the special handling of above 4G resources during phase 2 of the allocator. Which saves us about 20% of the code :D Change-Id: I4c7fcd1f5146f6cc287bd3aa5582da55bc5d6955 Signed-off-by: Nico Huber <nico.h@gmx.de> Reviewed-on: https://review.coreboot.org/c/coreboot/+/65413 Reviewed-by: Arthur Heymans <arthur@aheymans.xyz> Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org> |
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| 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 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:
- 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.