1=========== 2Usage Modes 3=========== 4 5The libc can used in two different modes: 6 7#. The **overlay** mode: In this mode, the link order semantics are exploited 8 to overlay implementations from LLVM's libc over the system libc. See 9 :ref:`overlay_mode` for more information about this mode. In this mode, libc 10 uses the ABI of the system it's being overlayed onto. Headers are NOT 11 generated. libllvmlibc.a is the only build artifact. 12#. The **fullbuild** mode: In this mode, LLVM's libc is used as the only libc 13 for the binary. See :ref:`fullbuild_mode` for information about this mode. 14 In this mode, libc uses its own ABI. Headers are generated along with a 15 libc.a. 16