# # Architectures that offer an FTRACE implementation should select HAVE_FTRACE: # config HAVE_FTRACE bool config TRACING bool select DEBUG_FS config FTRACE bool "Kernel Function Tracer" depends on DEBUG_KERNEL && HAVE_FTRACE select FRAME_POINTER select TRACING help Enable the kernel to trace every kernel function. This is done by using a compiler feature to insert a small, 5-byte No-Operation instruction to the beginning of every kernel function, which NOP sequence is then dynamically patched into a tracer call when tracing is enabled by the administrator. If it's runtime disabled (the bootup default), then the overhead of the instructions is very small and not measurable even in micro-benchmarks.