build: support pre-built host tools

Right now the build system builds the host tools over and over again, in some
environments especially when running in an IDE on windows for example,
this is not desired and a set of pre-built host tools should be used.

Provide an option to use pre-built tools instead of building them
from source.

To use, set PREBUILT_HOST_TOOLS to the path where all pre-built host tools
are hosted. To get a prebuilt version of the host tools, build without the
variable set and copy the generated host binaries from outdir. The following
tools are supported:

* conf
* fixdep
* gen_idt
* gen_offset_header

Jira: ZEP-237
Change-Id: Iea505bfd0b50f851ee2781b5117bb6085ab20157
Signed-off-by: Anas Nashif <anas.nashif@intel.com>

Makefile

@@ -316,8 +316,15 @@ OBJDUMP		= $(CROSS_COMPILE)objdump
 GDB		= $(CROSS_COMPILE)gdb
 READELF		= $(CROSS_COMPILE)readelf
 AWK		= awk
+ifeq ($(PREBUILT_HOST_TOOLS),)
 GENIDT		= scripts/gen_idt/gen_idt
 GENOFFSET_H	= scripts/gen_offset_header/gen_offset_header
+FIXDEP		= scripts/basic/fixdep
+else
+GENIDT		= $(PREBUILT_HOST_TOOLS)/gen_idt
+GENOFFSET_H	= $(PREBUILT_HOST_TOOLS)/gen_offset_header
+FIXDEP		= $(PREBUILT_HOST_TOOLS)/fixdep
+endif
 PERL		= perl
 PYTHON		= python
 CHECK		= sparse
@@ -406,7 +413,7 @@ exports += HOSTCXX HOSTCXXFLAGS CHECK CHECKFLAGS
 
 exports += KBUILD_CPPFLAGS NOSTDINC_FLAGS ZEPHYRINCLUDE OBJCOPYFLAGS LDFLAGS
 exports += KBUILD_CFLAGS KBUILD_CXXFLAGS CFLAGS_GCOV KBUILD_AFLAGS AFLAGS_KERNEL
-exports += KBUILD_ARFLAGS
+exports += KBUILD_ARFLAGS FIXDEP
 
 # Push the exports to sub-processes
 export $(exports)
@@ -438,10 +445,14 @@ export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
 
 # Basic helpers built in scripts/
 PHONY += scripts_basic
+ifeq ($(PREBUILT_HOST_TOOLS),)
 scripts_basic:
 	$(Q)$(MAKE) $(build)=scripts/basic
 	$(Q)$(MAKE) $(build)=scripts/gen_idt
 	$(Q)$(MAKE) $(build)=scripts/gen_offset_header
+else
+scripts_basic:
+endif
 
 # To avoid any implicit rule to kick in, define an empty command.
 scripts/basic/%: scripts_basic ;

scripts/Kbuild.include

@@ -255,7 +255,7 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
 if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
 	@set -e;                                                             \
 	$(echo-cmd) $(cmd_$(1));                                             \
-	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
+	$(FIXDEP) $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
 	rm -f $(depfile);                                                    \
 	mv -f $(dot-target).tmp $(dot-target).cmd)
 

scripts/Makefile.build

@@ -172,7 +172,7 @@ define rule_cc_o_c
 	$(cmd_modversions)						  \
 	$(call echo-cmd,record_mcount)					  \
 	$(cmd_record_mcount)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
+	$(FIXDEP) $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
 	                                              $(dot-target).tmp;  \
 	rm -f $(depfile);						  \
 	mv -f $(dot-target).tmp $(dot-target).cmd
@@ -212,7 +212,7 @@ $(call echo-cmd,cc_o_cxx) $(cmd_cc_o_cxx);				  \
 	$(cmd_modversions)						  \
 	$(call echo-cmd,record_mcount)					  \
 	$(cmd_record_mcount)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_cxx)' >    \
+	$(FIXDEP) $(depfile) $@ '$(call make-cmd,cc_o_cxx)' >    \
 	                                              $(dot-target).tmp;  \
 	rm -f $(depfile);						  \
 	mv -f $(dot-target).tmp $(dot-target).cmd

scripts/kconfig/Makefile

@@ -19,40 +19,46 @@ endif
 # We need this, in case the user has it in its environment
 unexport CONFIG_
 
-xconfig: $(obj)/qconf
+ifneq ($(PREBUILT_HOST_TOOLS),)
+KCONFIG_BIN_PATH = $(PREBUILT_HOST_TOOLS)
+else
+KCONFIG_BIN_PATH = $(obj)
+endif
+
+xconfig: $(KCONFIG_BIN_PATH)/qconf
 	$< $(Kconfig)
 
-gconfig: $(obj)/gconf
+gconfig: $(KCONFIG_BIN_PATH)/gconf
 	$< $(Kconfig)
 
-menuconfig: $(obj)/mconf
+menuconfig: $(KCONFIG_BIN_PATH)/mconf
 	$< $(Kconfig)
 
-config: $(obj)/conf
+config: $(KCONFIG_BIN_PATH)/conf
 	$< --oldaskconfig $(Kconfig)
 
-nconfig: $(obj)/nconf
+nconfig: $(KCONFIG_BIN_PATH)/nconf
 	$< $(Kconfig)
 
-oldconfig: $(obj)/conf
+oldconfig: $(KCONFIG_BIN_PATH)/conf
 	$< --$@ $(Kconfig)
 
-silentoldconfig: $(obj)/conf
+silentoldconfig: $(KCONFIG_BIN_PATH)/conf
 	$(Q)mkdir -p include/config include/generated
 	$< --$@ $(Kconfig)
 
-localyesconfig localmodconfig: $(obj)/streamline_config.pl $(obj)/conf
+localyesconfig localmodconfig: $(KCONFIG_BIN_PATH)/streamline_config.pl $(KCONFIG_BIN_PATH)/conf
 	$(Q)mkdir -p include/config include/generated
 	$(Q)perl $< --$@ $(srctree) $(Kconfig) > .tmp.config
 	$(Q)if [ -f .config ]; then 					\
 			cmp -s .tmp.config .config ||			\
 			(mv -f .config .config.old.1;			\
 			 mv -f .tmp.config .config;			\
-			 $(obj)/conf --silentoldconfig $(Kconfig);	\
+			 $(KCONFIG_BIN_PATH)/conf --silentoldconfig $(Kconfig);	\
 			 mv -f .config.old.1 .config.old)		\
 	else								\
 			mv -f .tmp.config .config;			\
-			$(obj)/conf --silentoldconfig $(Kconfig);	\
+			$(KCONFIG_BIN_PATH)/conf --silentoldconfig $(Kconfig);	\
 	fi
 	$(Q)rm -f .tmp.config
 
@@ -65,40 +71,40 @@ update-po-config: $(obj)/kxgettext $(obj)/gconf.glade.h
 	    --from-code=UTF-8                                       \
 	    --files-from=$(srctree)/scripts/kconfig/POTFILES.in     \
 	    --directory=$(srctree) --directory=$(objtree)           \
-	    --output $(obj)/config.pot
+	    --output $(KCONFIG_BIN_PATH)/config.pot
-	$(Q)sed -i s/CHARSET/UTF-8/ $(obj)/config.pot
+	$(Q)sed -i s/CHARSET/UTF-8/ $(KCONFIG_BIN_PATH)/config.pot
 	$(Q)(for i in `ls $(srctree)/arch/*/Kconfig      \
 	    $(srctree)/arch/*/um/Kconfig`;               \
 	    do                                           \
 		echo "  GEN     $$i";                    \
 		$(obj)/kxgettext $$i                     \
-		     >> $(obj)/config.pot;               \
+		     >> $(KCONFIG_BIN_PATH)/config.pot;               \
 	    done )
 	$(Q)echo "  GEN     linux.pot"
-	$(Q)msguniq --sort-by-file --to-code=UTF-8 $(obj)/config.pot \
+	$(Q)msguniq --sort-by-file --to-code=UTF-8 $(KCONFIG_BIN_PATH)/config.pot \
 	    --output $(obj)/linux.pot
-	$(Q)rm -f $(obj)/config.pot
+	$(Q)rm -f $(KCONFIG_BIN_PATH)/config.pot
 
 PHONY += allnoconfig allyesconfig allmodconfig alldefconfig randconfig
 
-allnoconfig allyesconfig allmodconfig alldefconfig randconfig: $(obj)/conf
+allnoconfig allyesconfig allmodconfig alldefconfig randconfig: $(KCONFIG_BIN_PATH)/conf
 	$< --$@ $(Kconfig)
 
 PHONY += listnewconfig olddefconfig oldnoconfig savedefconfig defconfig
 
-listnewconfig olddefconfig: $(obj)/conf
+listnewconfig olddefconfig: $(KCONFIG_BIN_PATH)/conf
 	$< --$@ $(Kconfig)
 
 # oldnoconfig is an alias of olddefconfig, because people already are dependent
 # on its behavior(sets new symbols to their default value but not 'n') with the
 # counter-intuitive name.
-oldnoconfig: $(obj)/conf
+oldnoconfig: $(KCONFIG_BIN_PATH)/conf
 	$< --olddefconfig $(Kconfig)
 
-savedefconfig: $(obj)/conf
+savedefconfig: $(KCONFIG_BIN_PATH)/conf
 	$< --$@=defconfig $(Kconfig)
 
-defconfig: $(obj)/conf
+defconfig: $(KCONFIG_BIN_PATH)/conf
 ifeq ($(KBUILD_DEFCONFIG),)
 	$< --defconfig $(Kconfig)
 else
@@ -107,13 +113,13 @@ else
 endif
 defconfigfiles=$(wildcard $(srctree)/boards/*/$@)
 
-%_defconfig: $(obj)/conf
+%_defconfig: $(KCONFIG_BIN_PATH)/conf
 	$(if $(call defconfigfiles),, $(error No configuration exists for this board))
 	$(Q)$< --defconfig=$(defconfigfiles) $(Kconfig)
 
 configfiles=$(wildcard $(PROJECT_BASE)/$@ $(srctree)/kernel/configs/$@ $(srctree)/configs/$@)
 
-%.config: $(obj)/conf
+%.config: $(KCONFIG_BIN_PATH)/conf
 	$(if $(call configfiles),, $(error No configuration exists for this target on this architecture))
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m .config $(configfiles)
 	+$(Q)yes "" | $(MAKE) -f $(srctree)/Makefile oldconfig