MT7688 openwrt makefile 主要流程

1. openwrt_widora/Makefile

world: 主目标

include $(TOPDIR)/include/host.mk

ifneq ($(OPENWRT_BUILD),1) //第一次运行
_SINGLE=export MAKEFLAGS=$(space);

override OPENWRT_BUILD=1
export OPENWRT_BUILD
GREP_OPTIONS=
export GREP_OPTIONS
include $(TOPDIR)/include/debug.mk
include $(TOPDIR)/include/depends.mk
include $(TOPDIR)/include/toplevel.mk
else // OPENWRT_BUILD = 1,第一次运行以后执行下面
include rules.mk
include $(INCLUDE_DIR)/depends.mk
include $(INCLUDE_DIR)/subdir.mk
include target/Makefile
include package/Makefile
include tools/Makefile

include toolchain/Makefile

在这里引入了

include target/Makefile include package/Makefile include tools/Makefile include toolchain/Makefile

这些子目录里的Makefile使用include/subdir.mk里定义的两个函数来动态生成规则，这两个函数是subdir和stampfile

拿target/Makefile举例：

(eval(call stampfile,$(curdir),target,prereq,.config))

会生成规则：

target/stamp-prereq:=$(STAGING_DIR)/stamp/.target_prereq

$$(target/stamp-prereq): $(TMP_DIR)/.build .config

	@+$(SCRIPT_DIR)/timestamp.pl -n $$(target/stamp-prereq) target .config || \
		make $$(target/flags-prereq) target/prereq

	@mkdir -p $$$$(dirname $$(target/stamp-prereq))

	@touch $$(target/stamp-prereq)

$$(if $(call debug,target,v),,.SILENT: $$(target/stamp-prereq))
.PRECIOUS: $$(target/stamp-prereq) # work around a make bug

target//clean:=target/stamp-prereq/clean

target/stamp-prereq/clean: FORCE

	@rm -f $$(target/stamp-prereq)

拿target/Makefile举例：

(eval(call stampfile,$(curdir),target,prereq,.config))

会生成规则：

target/stamp-prereq:=$(STAGING_DIR)/stamp/.target_prereq

$$(target/stamp-prereq): $(TMP_DIR)/.build .config

	@+$(SCRIPT_DIR)/timestamp.pl -n $$(target/stamp-prereq) target .config || \
		make $$(target/flags-prereq) target/prereq

	@mkdir -p $$$$(dirname $$(target/stamp-prereq))

	@touch $$(target/stamp-prereq)

$$(if $(call debug,target,v),,.SILENT: $$(target/stamp-prereq))
.PRECIOUS: $$(target/stamp-prereq) # work around a make bug

target//clean:=target/stamp-prereq/clean

target/stamp-prereq/clean: FORCE

	@rm -f $$(target/stamp-prereq)

所以可以简单的看作： (eval(call stampfile,(curdir),target,prereq,.config))生成了目标(target/stamp-prereq)

对于target分别生成了：(target/stamp-preq)，(target/stamp-copile)， $(target/stamp-install)
toolchain : $(toolchain/stamp-install)
package : (package/stamp?preq),(package/stamp-cleanup), (package/stamp?compile),(package/stamp-install)
tools : $(tools/stamp-install)

OpenWrt的主Makefile工作过程

subdir

subdir这个函数写了一大堆东西，看起来很复杂。

$(call subdir, target) 会遍历下的子目录，执行 make -C 操作。这样就切入子目录中去了

MT7688 openwrt makefile 主要流程

subdir

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