kbuild: introduce Kbuild.include

Kbuild.include is a placeholder for definitions originally present in
both the top-level Makefile and scripts/Makefile.build.
There were a slight difference in the filechk definition, so the most videly
used version was kept and usr/Makefile was adopted for this syntax.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
---

7 files changed, 103 insertions, 167 deletions

diff --git a/Makefile b/Makefile
index 7e4624a14586..7c607dc64479 100644
--- a/Makefile
+++ b/Makefile
@@ -309,6 +309,9 @@ cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh \
 # Look for make include files relative to root of kernel src
 MAKEFLAGS += --include-dir=$(srctree)
 
+# We need some generic definitions
+include scripts/Kbuild.include
+
 # For maximum performance (+ possibly random breakage, uncomment
 # the following)
 
@@ -367,11 +370,6 @@ export AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 # even be read-only.
 export MODVERDIR := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_versions
 
-# The temporary file to save gcc -MD generated dependencies must not
-# contain a comma
-comma := ,
-depfile = $(subst $(comma),_,$(@D)/.$(@F).d)
-
 # Files to ignore in find ... statements
 
 RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS -o -name .pc \) -prune -o
@@ -1285,72 +1283,6 @@ ifneq ($(cmd_files),)
   include $(cmd_files)
 endif
 
-# Execute command and generate cmd file
-if_changed = $(if $(strip $? \
-                          $(filter-out $(cmd_$(1)),$(cmd_$@))\
-                          $(filter-out $(cmd_$@),$(cmd_$(1)))),\
-        @set -e; \
-        $(if $($(quiet)cmd_$(1)),echo '  $(subst ','\'',$($(quiet)cmd_$(1)))';) \
-        $(cmd_$(1)); \
-        echo 'cmd_$@ := $(subst $$,$$$$,$(subst ','\'',$(cmd_$(1))))' > $(@D)/.$(@F).cmd)
-
-
-# execute the command and also postprocess generated .d dependencies
-# file
-if_changed_dep = $(if $(strip $? $(filter-out FORCE $(wildcard $^),$^)\
-                          $(filter-out $(cmd_$(1)),$(cmd_$@))\
-                          $(filter-out $(cmd_$@),$(cmd_$(1)))),\
-        $(Q)set -e; \
-        $(if $($(quiet)cmd_$(1)),echo '  $(subst ','\'',$($(quiet)cmd_$(1)))';) \
-        $(cmd_$(1)); \
-        scripts/basic/fixdep $(depfile) $@ '$(subst $$,$$$$,$(subst ','\'',$(cmd_$(1))))' > $(@D)/.$(@F).tmp; \
-        rm -f $(depfile); \
-        mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd)
-
-# Usage: $(call if_changed_rule,foo)
-# will check if $(cmd_foo) changed, or any of the prequisites changed,
-# and if so will execute $(rule_foo)
-
-if_changed_rule = $(if $(strip $? \
-                               $(filter-out $(cmd_$(1)),$(cmd_$(@F)))\
-                               $(filter-out $(cmd_$(@F)),$(cmd_$(1)))),\
-                       $(Q)$(rule_$(1)))
-
-# If quiet is set, only print short version of command
-
-cmd = @$(if $($(quiet)cmd_$(1)),echo '  $($(quiet)cmd_$(1))' &&) $(cmd_$(1))
-
-# filechk is used to check if the content of a generated file is updated.
-# Sample usage:
-# define filechk_sample
-#       echo $KERNELRELEASE
-# endef
-# version.h : Makefile
-#       $(call filechk,sample)
-# The rule defined shall write to stdout the content of the new file.
-# The existing file will be compared with the new one.
-# - If no file exist it is created
-# - If the content differ the new file is used
-# - If they are equal no change, and no timestamp update
-
-define filechk
-        @set -e;                                \
-        echo '  CHK     $@';                    \
-        mkdir -p $(dir $@);                     \
-        $(filechk_$(1)) < $< > $@.tmp;          \
-        if [ -r $@ ] && cmp -s $@ $@.tmp; then  \
-                rm -f $@.tmp;                   \
-        else                                    \
-                echo '  UPD     $@';            \
-                mv -f $@.tmp $@;                \
-        fi
-endef
-
-# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=dir
-# Usage:
-# $(Q)$(MAKE) $(build)=dir
-build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
-
 # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.clean obj=dir
 # Usage:
 # $(Q)$(MAKE) $(clean)=dir
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
new file mode 100644
index 000000000000..9087273abf91
--- /dev/null
+++ b/scripts/Kbuild.include
@@ -0,0 +1,96 @@
+####
+# kbuild: Generic definitions
+
+# Convinient variables
+comma   := ,
+empty   :=
+space   := $(empty) $(empty)
+
+###
+# The temporary file to save gcc -MD generated dependencies must not
+# contain a comma
+depfile = $(subst $(comma),_,$(@D)/.$(@F).d)
+
+###
+# filechk is used to check if the content of a generated file is updated.
+# Sample usage:
+# define filechk_sample
+#       echo $KERNELRELEASE
+# endef
+# version.h : Makefile
+#       $(call filechk,sample)
+# The rule defined shall write to stdout the content of the new file.
+# The existing file will be compared with the new one.
+# - If no file exist it is created
+# - If the content differ the new file is used
+# - If they are equal no change, and no timestamp update
+# - stdin is piped in from the first prerequisite ($<) so one has
+#   to specify a valid file as first prerequisite (often the kbuild file)
+define filechk
+        $(Q)set -e;                             \
+        echo '  CHK     $@';                    \
+        mkdir -p $(dir $@);                     \
+        $(filechk_$(1)) < $< > $@.tmp;          \
+        if [ -r $@ ] && cmp -s $@ $@.tmp; then  \
+                rm -f $@.tmp;                   \
+        else                                    \
+                echo '  UPD     $@';            \
+                mv -f $@.tmp $@;                \
+        fi
+endef
+
+###
+# Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
+# Usage:
+# $(Q)$(MAKE) $(build)=dir
+build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
+
+# If quiet is set, only print short version of command
+cmd = @$(if $($(quiet)cmd_$(1)),\
+      echo '  $(subst ','\'',$($(quiet)cmd_$(1)))' &&) $(cmd_$(1))
+
+###
+# if_changed      - execute command if any prerequisite is newer than 
+#                   target, or command line has changed
+# if_changed_dep  - as if_changed, but uses fixdep to reveal dependencies
+#                   including used config symbols
+# if_changed_rule - as if_changed but execute rule instead
+# See Documentation/kbuild/makefiles.txt for more info
+
+ifneq ($(KBUILD_NOCMDDEP),1)
+# Check if both arguments has same arguments. Result in empty string if equal
+# User may override this check using make KBUILD_NOCMDDEP=1
+arg-check = $(strip $(filter-out $(1), $(2)) $(filter-out $(2), $(1)) )
+endif
+
+# echo command. Short version is $(quiet) equals quiet, otherwise full command
+echo-cmd = $(if $($(quiet)cmd_$(1)), \
+        echo '  $(subst ','\'',$($(quiet)cmd_$(1)))';)
+
+# function to only execute the passed command if necessary
+# >'< substitution is for echo to work, >$< substitution to preserve $ when reloading .cmd file
+# note: when using inline perl scripts [perl -e '...$$t=1;...'] in $(cmd_xxx) double $$ your perl vars
+# 
+if_changed = $(if $(strip $? $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \
+        @set -e; \
+        $(echo-cmd) \
+        $(cmd_$(1)); \
+        echo 'cmd_$@ := $(subst $$,$$$$,$(subst ','\'',$(cmd_$(1))))' > $(@D)/.$(@F).cmd)
+
+# execute the command and also postprocess generated .d dependencies
+# file
+if_changed_dep = $(if $(strip $? $(filter-out FORCE $(wildcard $^),$^)\
+        $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),                  \
+        @set -e; \
+        $(echo-cmd) \
+        $(cmd_$(1)); \
+        scripts/basic/fixdep $(depfile) $@ '$(subst $$,$$$$,$(subst ','\'',$(cmd_$(1))))' > $(@D)/.$(@F).tmp; \
+        rm -f $(depfile); \
+        mv -f $(@D)/.$(@F).tmp $(@D)/.$(@F).cmd)