CPU optimization flags

▶ A set of cross-compiling tools is specific to a CPU architecture (ARM, x86, MIPS, PowerPC) ▶ However, with the -march=, -mcpu=, -mtune= options, one can select more precisely the target CPU type ▶ For example, -march=armv7 -mcpu=cortex-a8 ▶ At the toolchain compilation time, values can be chosen. They are used: ▶ As the default values for the cross-compiling tools, when no other -march, -mcpu, -mtune options are passed ▶ To compile the C library ▶ Even if the C library has been compiled for armv5t, it doesn't prevent from compiling other programs for armv7