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fe2fc83936
When CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH is set, vbnv_cmos will try to load VBNV from flash if the VBNV in CMOS is invalid. This is usually correct, except the case of battery cut-off. CMOS will always be invalid after battery cut-off if there is no RTC battery (or if that is dead). However, in current implementation the backup in flash is only updated in coreboot, while the real battery cutoff (and the clearing of cutoff flags in VBNV) is done in payload (Depthcharge) stage. This will create an endless reboot loop that: 1. crossystem sets battery cutoff flag in VBNV_CMOS then reboot. 2. coreboot backs-up VBNV_CMOS to VBNV_flash. 3. Depthcharge sees cutoff flag in VBNV_CMOS. 4. Depthcharge clears cutoff flag in VBNV_CMOS. 5. Depthcharge performs battery cutoff (CMOS data is lost). 6. (Plug AC adapter) Reboot. 7. Coreboot sees invalid VBNV_CMOS, load backup from VBNV_flash. 8. Jump to 3. As a result, we should always clear battery cutoff flags when loading backups from VBNV_flash. BRANCH=glados,reef BUG=chrome-os-partner:61365,chrome-os-partner:59615 TEST=emerge-reef coreboot bootimage; Change-Id: I3250a3a179a7b0de9c6e401e4a94dcd23920e473 Signed-off-by: Hung-Te Lin <hungte@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/423460 Reviewed-by: Duncan Laurie <dlaurie@google.com> Reviewed-on: https://review.coreboot.org/18008 Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com> |
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3rdparty | ||
configs | ||
Documentation | ||
payloads | ||
src | ||
util | ||
.checkpatch.conf | ||
.clang-format | ||
.gitignore | ||
.gitmodules | ||
.gitreview | ||
COPYING | ||
gnat.adc | ||
MAINTAINERS | ||
Makefile | ||
Makefile.inc | ||
README | ||
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 http://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: * http://www.coreboot.org/Supported_Motherboards * http://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_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case). * iasl (for targets with ACPI support) Optional: * doxygen (for generating/viewing documentation) * gdb (for better debugging facilities on some targets) * ncurses (for 'make menuconfig' and 'make nconfig') * flex and bison (for regenerating parsers) Building coreboot ----------------- Please consult http://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 http://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: http://www.coreboot.org You can contact us directly on the coreboot mailing list: http://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.