+NAME =
+
+# *DOCUMENTATION*
+# To see a list of typical targets execute "make help"
+# More info can be located in ./README
+# Comments in this file are targeted only to the developer, do not
+# expect to learn how to build the kernel reading this file.
+
+# Do not:
+# o use make's built-in rules and variables
+# (this increases performance and avoids hard-to-debug behaviour);
+# o print "Entering directory ...";
+MAKEFLAGS += -rR --no-print-directory
+
+# Avoid funny character set dependencies
+unexport LC_ALL
+LC_COLLATE=C
+LC_NUMERIC=C
+export LC_COLLATE LC_NUMERIC
+
+# We are using a recursive build, so we need to do a little thinking
+# to get the ordering right.
+#
+# Most importantly: sub-Makefiles should only ever modify files in
+# their own directory. If in some directory we have a dependency on
+# a file in another dir (which doesn't happen often, but it's often
+# unavoidable when linking the built-in.o targets which finally
+# turn into vmlinux), we will call a sub make in that other dir, and
+# after that we are sure that everything which is in that other dir
+# is now up to date.
+#
+# The only cases where we need to modify files which have global
+# effects are thus separated out and done before the recursive
+# descending is started. They are now explicitly listed as the
+# prepare rule.
+
+# To put more focus on warnings, be less verbose as default
+# Use 'make V=1' to see the full commands
+
+ifeq ("$(origin V)", "command line")
+ KBUILD_VERBOSE = $(V)
+endif
+ifndef KBUILD_VERBOSE
+ KBUILD_VERBOSE = 0
+endif
+
+# Call a source code checker (by default, "sparse") as part of the
+# C compilation.
+#
+# Use 'make C=1' to enable checking of only re-compiled files.
+# Use 'make C=2' to enable checking of *all* source files, regardless
+# of whether they are re-compiled or not.
+#
+# See the file "Documentation/sparse.txt" for more details, including
+# where to get the "sparse" utility.
+
+ifeq ("$(origin C)", "command line")
+ KBUILD_CHECKSRC = $(C)
+endif
+ifndef KBUILD_CHECKSRC
+ KBUILD_CHECKSRC = 0
+endif
+
+# Use make M=dir to specify directory of external module to build
+# Old syntax make ... SUBDIRS=$PWD is still supported
+# Setting the environment variable KBUILD_EXTMOD take precedence
+ifdef SUBDIRS
+ KBUILD_EXTMOD ?= $(SUBDIRS)
+endif
+
+ifeq ("$(origin M)", "command line")
+ KBUILD_EXTMOD := $(M)
+endif
+
+# kbuild supports saving output files in a separate directory.
+# To locate output files in a separate directory two syntaxes are supported.
+# In both cases the working directory must be the root of the kernel src.
+# 1) O=
+# Use "make O=dir/to/store/output/files/"
+#
+# 2) Set KBUILD_OUTPUT
+# Set the environment variable KBUILD_OUTPUT to point to the directory
+# where the output files shall be placed.
+# export KBUILD_OUTPUT=dir/to/store/output/files/
+# make
+#
+# The O= assignment takes precedence over the KBUILD_OUTPUT environment
+# variable.
+
+
+# KBUILD_SRC is set on invocation of make in OBJ directory
+# KBUILD_SRC is not intended to be used by the regular user (for now)
+ifeq ($(KBUILD_SRC),)
+
+# OK, Make called in directory where kernel src resides
+# Do we want to locate output files in a separate directory?
+ifeq ("$(origin O)", "command line")
+ KBUILD_OUTPUT := $(O)
+endif
+
+ifeq ("$(origin W)", "command line")
+ export KBUILD_ENABLE_EXTRA_GCC_CHECKS := $(W)
+endif
+
+# That's our default target when none is given on the command line
+PHONY := _all
+_all:
+
+# Cancel implicit rules on top Makefile
+$(CURDIR)/Makefile Makefile: ;
+
+ifneq ($(KBUILD_OUTPUT),)
+# Invoke a second make in the output directory, passing relevant variables
+# check that the output directory actually exists
+saved-output := $(KBUILD_OUTPUT)
+KBUILD_OUTPUT := $(shell cd $(KBUILD_OUTPUT) && /bin/pwd)
+$(if $(KBUILD_OUTPUT),, \
+ $(error output directory "$(saved-output)" does not exist))
+
+PHONY += $(MAKECMDGOALS) sub-make
+
+$(filter-out _all sub-make $(CURDIR)/Makefile, $(MAKECMDGOALS)) _all: sub-make
+ @:
+
+sub-make: FORCE
+ $(if $(KBUILD_VERBOSE:1=),@)$(MAKE) -C $(KBUILD_OUTPUT) \
+ KBUILD_SRC=$(CURDIR) \
+ KBUILD_EXTMOD="$(KBUILD_EXTMOD)" -f $(CURDIR)/Makefile \
+ $(filter-out _all sub-make,$(MAKECMDGOALS))
+
+# Leave processing to above invocation of make
+skip-makefile := 1
+endif # ifneq ($(KBUILD_OUTPUT),)
+endif # ifeq ($(KBUILD_SRC),)
+
+# We process the rest of the Makefile if this is the final invocation of make
+ifeq ($(skip-makefile),)
+
+# If building an external module we do not care about the all: rule
+# but instead _all depend on modules
+PHONY += all
+ifeq ($(KBUILD_EXTMOD),)
+_all: all