18 400 True 0 0 True 5 vertical 10 True vertical True The CFLAGS and CXXFLAGS variables define the optimization flags for the gcc C and C++ compiler respectively. center 0 True True automatic automatic True 3 2 True True vertical True True True -march= False True True True True False True True True vertical True True True -O False True True 2 0 1 2 3 s True True False True 1 2 True True vertical -pipe True True False True False True 2 3 True True True Specifies the name of the target architecture. “native” will build binaries optimized for this CPU but they won't run on any other CPU. False True 1 2 5 True True True Specifies the optimization class. Every class has the same optimizations as the one before plus some extras (-Os has all the optimizations of -O2 which don't increase the size of the generated code). Don't set -O3 system-wide, it is known to break builds, resulting in unstable code. -O2 is recommended. False True 1 2 1 2 5 True True True Increases the speed at which the compilation runs by using pipes instead of temporary files, at the exception of increased memory use. False True 1 2 2 3 5 1 0 True vertical True The MAKEOPTS let you define various options passed to make when compiling. 0 True True automatic automatic True 3 2 True True vertical True True True -j False True True True True True True False True True True vertical True True True -l False True True True True True True False True 1 2 True True vertical -s True True False True False True 2 3 True True True Allow this many jobs (e.g. parallel compilations) at once; infinite jobs with 0. A good choice is the number of CPUs (or CPU cores) in your system plus one, but this guideline isn't always perfect. False True 1 2 5 True True True Don't start multiple jobs unless load is below this much. Do not set both -j and -l to zero. False True 1 2 1 2 5 True True True Don't echo recipes, resulting in a quieter output (errors will still be printed). False True 1 2 2 3 5 1 1