This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / scripts / Makefile.lib

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 3a7663b..7cf75cc 100644 (file)
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -183,15 +183,24 @@ cmd_gzip = gzip -f -9 < $< > $@
 # Generic stuff
 # ===========================================================================
 
+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 $? \
-                         $(filter-out $(cmd_$(1)),$(cmd_$@))\
-                         $(filter-out $(cmd_$@),$(cmd_$(1)))),\
+# 
+if_changed = $(if $(strip $? $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ), \
        @set -e; \
-       $(if $($(quiet)cmd_$(1)),echo '  $(subst ','\'',$($(quiet)cmd_$(1)))';) \
+       $(echo-cmd) \
        $(cmd_$(1)); \
        echo 'cmd_$@ := $(subst $$,$$$$,$(subst ','\'',$(cmd_$(1))))' > $(@D)/.$(@F).cmd)
 
@@ -200,10 +209,9 @@ if_changed = $(if $(strip $? \
 # file
 
 if_changed_dep = $(if $(strip $? $(filter-out FORCE $(wildcard $^),$^)\
-                         $(filter-out $(cmd_$(1)),$(cmd_$@))\
-                         $(filter-out $(cmd_$@),$(cmd_$(1)))),\
+       $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),                  \
        @set -e; \
-       $(if $($(quiet)cmd_$(1)),echo '  $(subst ','\'',$($(quiet)cmd_$(1)))';) \
+       $(echo-cmd) \
        $(cmd_$(1)); \
        scripts/basic/fixdep $(depfile) $@ '$(subst $$,$$$$,$(subst ','\'',$(cmd_$(1))))' > $(@D)/.$(@F).tmp; \
        rm -f $(depfile); \
@@ -213,9 +221,7 @@ if_changed_dep = $(if $(strip $? $(filter-out FORCE $(wildcard $^),$^)\
 # 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)),$(cmd_$@))\
-                              $(filter-out $(cmd_$@),$(cmd_$(1)))),\
+if_changed_rule = $(if $(strip $? $(call arg-check, $(cmd_$(1)), $(cmd_$@)) ),\
                        @set -e; \
                        $(rule_$(1)))
 
@@ -232,3 +238,30 @@ descend =$(Q)$(MAKE) -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build ob
 # Usage:
 # $(Q)$(MAKE) $(build)=dir
 build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
+
+# 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
+       $(Q)set -e;                             \
+       echo '  CHK     $@';                    \
+       mkdir -p $(dir $@);                     \
+       $(filechk_$(1)) $(2) > $@.tmp;          \
+       if [ -r $@ ] && cmp -s $@ $@.tmp; then  \
+               rm -f $@.tmp;                   \
+       else                                    \
+               echo '  UPD     $@';            \
+               mv -f $@.tmp $@;                \
+       fi
+endef
+