967753f0d8
From Skylake/Sunrise Point onwards, there are two BIOS_CNTL registers: one on the LPC/eSPI PCI device, and another on the SPI PCI device. When the WPD bit changes from 0 to 1 and the LE bit is set, the PCH raises a TCO SMI with the BIOSWR_STS bit set. However, the BIOSWR_STS bit is not set when the TCO SMI comes from the SPI or eSPI controller instead, but a status bit in the BIOS_CNTL register gets set. If the SMI cause is not handled, another SMI will happen immediately after returning from the SMI handler, which results in a deadlock. Prevent deadlocks by clearing the SPI synchronous SMI status bit in the SMI handler. When SPI raises a synchronous SMI, the TCO_STS bit in the SMI_STS register is continously set until the SPI synchronous SMI status bit is cleared. To not risk missing any other TCO SMIs, do not clear the TCO_STS bit again in the same SMI handler invocation. If the TCO_STS bit remains set when returning from SMM, another SMI immediately happens and clears the TCO_STS bit, handling any pending events. SPI can also generate asynchronous SMIs when the WPD bit is cleared and one attempts to write to flash using SPI hardware sequencing. This patch does not account for SPI asynchronous SMIs, because they are disabled by default and cannot be enabled once the BIOS Interface Lock-Down bit in the BIOS_CNTL register has been set, which coreboot already does. These asynchronous SMIs set the SPI_STS bit of the SMI_STS register. Clearing the SPI asynchronous SMI source should be done inside the SPI_STS SMI handler, which is currently not implemented. All of this goes out of the scope of this patch, and is currently not necessary anyway. This patch does not handle eSPI because I cannot test it, and knowing if a board uses LPC or eSPI from common code is currently not possible, and this is beyond the scope of what this commit tries to achieve (fix SPI). Tested on HP 280 G2, no longer deadlocks when SMM BIOS write protection is on. Write protection will be enforced in a follow-up. Change-Id: Iec498674ae70f6590c33a6bf4967876268f2b0c8 Signed-off-by: Angel Pons <th3fanbus@gmail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/50754 Reviewed-by: Michael Niewöhner <foss@mniewoehner.de> Reviewed-by: Nico Huber <nico.h@gmx.de> Tested-by: build bot (Jenkins) <no-reply@coreboot.org> |
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| configs | ||
| Documentation | ||
| LICENSES | ||
| payloads | ||
| src | ||
| tests | ||
| util | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| AUTHORS | ||
| COPYING | ||
| gnat.adc | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc | ||
| README.md | ||
| toolchain.inc | ||
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.