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The 'm' (a memory reference) constraint makes little sense here since we are talking about a fs relative read, rather 'ir' (immediate or register) constraint is more sensible. N.B. The 'p' constraint allows anything which fits the form of an address calculation where the 'ir' constraint is just a register /xor/ immediate. Hence would produce better code here however, unfortunately, clang does not currently support it properly. The %b and %w constraints are also redundant and only hide errors. The functions writefsword() and writefsdword() should use ir instead of iq. iq is unnecessarily restrictive (it is only required for writing bytes). The cld in stosb is redundant (and the constraints are unnecessarily complicated). Note that The ABI guarantees that the direction flag is cleared. i.e. eax, ecx, edx are caller-saved, returned value in eax, eax+edx, st0, yaddayadda, direction flag cleared. In fact bad things can happen if you set it in some asm and do not clear it until the end of the asm. Line wrap these extraneously long lines found with these particular functions. Many thanks to Christoph Mallon <christoph.mallon@gmx.de> from #llvm for helping me with this. Change-Id: Iaf3ad65791640e1060a2029e7ebb043f57b338a9 Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com> Reviewed-on: http://review.coreboot.org/5758 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org> Reviewed-by: Marc Jones <marc.jones@se-eng.com>
------------------------------------------------------------------------------- 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.