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Khem Raj
156a2d9860
tune files which inherit the arch definitions already define appropriate -mcpu option, which is equivalent of right -march and -mtune combination and is preferred since gcc is getting stricter and stricter with option check semantics and can now find incompatible -march and -mcpu options better with every release. It does internal feature consistency check and if it finds out discrepency between what -mcpu would expand to as compared to -march it will flag the options to be incompatible, for naked eye it sounds wrong but gcc would translate -mcpu to a given -march internally and it might not match to what we set in these arch files. The effects are quite subtle, where this can result in configure test failing to compile due to these incompatible options and a feature option getting disabled for a recipe for no reason. e.g. with gcc9 which can now detect that -mcpu=cortex-a5 and -march=armv7-a are incompatible, many features in libstdc++ ends up disabled due to configure check failures e.g. size_t size, ptrdiff_t sizes, which inturn results in compiling libstdc++ with unwanted disabled features. (From OE-Core rev: ac83d22eb5031f7fdd09d34a1a46d92fd3e39a3c) Signed-off-by: Khem Raj <raj.khem@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
QEMU Emulation Targets ====================== To simplify development, the build system supports building images to work with the QEMU emulator in system emulation mode. Several architectures are currently supported in 32 and 64 bit variants: * ARM (qemuarm + qemuarm64) * x86 (qemux86 + qemux86-64) * PowerPC (qemuppc only) * MIPS (qemumips + qemumips64) Use of the QEMU images is covered in the Yocto Project Reference Manual. The appropriate MACHINE variable value corresponding to the target is given in brackets.