No description
7756fe70eb
The code in src/cpu/x86/mtrr/mtrr.c disables caching in a few places when changing mtrr settings. While I can't find anything that says that's actually required, I can believe it's necessary. With that said, other code around the wrmsr instructions which actually modify the settings should be able to run with caching enabled with no ill effects. This is particularly true for two calls to printk, one in the fixed mtrr code and one in the variable, which could result in an arbitrary amount of work being done without caching. When changing the implementation of the cbmem console, these two printks caused a significant regression in boot performance on link of about 70ms which is about 10% of total firmware boot time. When the window where the cache is disabled is minimized, both this and the new implementation were about 30ms faster than the original boot time. For the variable MTRRs, we now store what we want to set the MSRs to and then write them all at once at the end of commit_var_mtrrs(). This way we don't have some set and some not, but we still minimize the time we spend with the caches disabled. Change-Id: I5139b262bd2d13f79afd88e2e2c0f514fb3e27c9 Signed-off-by: Gabe Black <gabeblack@google.com> Reviewed-on: https://chromium-review.googlesource.com/187811 Reviewed-by: Ronald Minnich <rminnich@chromium.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org> Commit-Queue: Gabe Black <gabeblack@chromium.org> Tested-by: Gabe Black <gabeblack@chromium.org> (cherry picked from commit 31529d6d965676c6cedeb62137eabc26819956fc) Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com> Reviewed-on: http://review.coreboot.org/6952 Tested-by: build bot (Jenkins) Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com> |
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| 3rdparty@f37e0e64ac | ||
| documentation | ||
| payloads | ||
| src | ||
| util | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| COPYING | ||
| 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 ------------------ * gcc / g++ * make Optional: * doxygen (for generating/viewing documentation) * iasl (for targets with ACPI support) * gdb (for better debugging facilities on some targets) * ncurses (for 'make menuconfig') * 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.