541f2f74a3
The current initialization of the 'equals' counter is incorrect, so that when 'equals >= SSZ * SSZ', the pixels in the sample array might not be all the same, leading to a wrong pixel value being set in the framebuffer. The 'equals' counter stores the number of latest pixels that were exactly equal. Within the for loop of 'ox', the sample array is updated in a column-based order, and the 'equals' counter is updated accordingly. However, the 'equals' counter is initialized in a row-based order, which causes it to be set too large than it should be. Consider the example where sample[sx][sy] are initially: [X X X A A A] // sy = 0 [X X X B B B] [X X X B B B] [X X X B B B] [X X X B B B] [X X X B B B] // sy = SSZ Then, the correct implementation will initialize 'equals' to be 15, with last_equal being B. Suppose all of the remaining pixels are B. Then, at the end of the 'while (fpfloor(ixfp) > ix)' loop when ix = 4, or equivalently after 4 more columns of sample are updated, 'equals' will be 15 + 6 * 4 = 39, which is greater than SSZ * SSZ = 36, but we can see there are still 2 A's in the sample: [B B B B A A] [B B B B B B] [B B B B B B] [B B B B B B] [B B B B B B] [B B B B B B] Therefore, we must also initialize the 'equals' counter in a column-based order. BUG=b:167739127 TEST=emerge-puff libpayload TEST=Character 'k' is rendered correctly on puff BRANCH=zork Change-Id: Ibc91ad1af85adcf093eff40797cd54f32f57111d Signed-off-by: Yu-Ping Wu <yupingso@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/45235 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Julius Werner <jwerner@chromium.org> |
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| Documentation | ||
| LICENSES | ||
| configs | ||
| payloads | ||
| src | ||
| tests | ||
| util | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| 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:
- 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.