arch.x86_64

# determines TARGET_CPU, if not forced by user
  if [ -z "${TARGET_CPU}" ]; then
    TARGET_CPU="x86-64"
  fi

# determine architecture's family
  TARGET_SUBARCH="x86_64"

  TARGET_GCC_ARCH="${TARGET_SUBARCH/-/}"
  TARGET_KERNEL_ARCH="x86"

# setup ARCH specific *FLAGS
  TARGET_CFLAGS="-march=${TARGET_CPU}"
  TARGET_LDFLAGS=""

# build with microarchitecture feature support defined by the TARGET_CPU value
# see https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/home for further details
  if [ -z "${TARGET_FEATURES}" ]; then
    TARGET_FEATURES="64bit cmov cx8 fpu fxsr mmx osfxsr sce sse sse2"
    TARGET_FEATURES_X86_64_V2="cmpxchg16b lahf-sahf popcnt sse3 sse4_1 sse4_2 ssse3"
    TARGET_FEATURES_X86_64_V3="avx avx2 bmi1 bmi2 f16c fma lzcnt movbe osxsave"
    if [ "${TARGET_CPU}" = "x86-64" ]; then
      TARGET_FEATURES+=" no_sahf"
    elif [ "${TARGET_CPU}" = "x86-64-v2" ]; then
      TARGET_FEATURES+=" ${TARGET_FEATURES_X86_64_V2}"
    elif [ "${TARGET_CPU}" = "x86-64-v3" ]; then
      TARGET_FEATURES+=" ${TARGET_FEATURES_X86_64_V2} ${TARGET_FEATURES_X86_64_V3}"
    fi
  fi
  TARGET_FEATURES="$(echo ${TARGET_FEATURES} | xargs -n1 | sort -u | xargs)"