cf65627ffa
The existing code sets DEVEN with the intention of enabling the IGD and
Mini-HD audio. However, according to the datasheet [1] and some testing
on hardware, the bits in DEVEN are set by default if and only if the
straps/fuses say the device should be enabled. To illustrate this, here
are a few initial values of DEVEN on some Haswell systems:
Supermicro X10SLM+-F: 0x0000002d
ASRock H81M-HDS: 0x00000039
Acer C720: 0x000000b1
On the X10SLM+-F, the IGD is disabled by default, and PEG10 & PEG11
are enabled by default. On the C720, the PEG devices are all disabled
by default, while the IGD and Mini-HD audio are already enabled.
There are two issues that result from the existing behaviour: PEG
devices are unconditionally disabled, and devices are set as enabled
when it's not actually possible to enable them.
So, don't touch the DEVEN register at this stage, as there are no
benefits.
Interestingly, on an Acer C720 (Google Peppy), a PCI device 00:04.0
appears. It is a thermal sensor. `powerstat` was used to measure idle
power usage over 30 minutes under Debian GNU/Linux 9.6. There was no
change in reported power draw.
[1] Desktop 4th Generation Intel® Core TM Processor Family, Desktop
Intel® Pentium® Processor Family, and Desktop Intel® Celeron®
Processor Family Datasheet – Volume 2 of 2.
December 2013, revision 003, document number 328898.
Change-Id: I242f9138472de5a0b26b5852f632b53b2920132d
Signed-off-by: Tristan Corrick <tristan@corrick.kiwi>
Reviewed-on: https://review.coreboot.org/c/30269
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
|
||
|---|---|---|
| 3rdparty | ||
| Documentation | ||
| configs | ||
| payloads | ||
| src | ||
| util | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| 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:
- https://www.coreboot.org/Supported_Motherboards
- https://www.coreboot.org/Supported_Chipsets_and_Devices
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.