uboot顶层makefile **/build-in.o是怎么编译出来的？

caijingkeji

顶层makefile中有如下模式匹配的代码：%.s: %.c prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.i: %.c prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.c prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.lst: %.c prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.s: %.S prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.S prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.symtypes: %.c prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)

# 关于 libs-y 变量
libs-y += drivers/serial/
libs-y += drivers/usb/dwc3/
libs-y += drivers/usb/emul/
libs-y += drivers/usb/eth/
....
libs-y                := $(patsubst %/, %/built-in.o, $(libs-y))
...
u-boot-main := $(libs-y)


所有目录被替换成了**/built-in.o,并且赋值给了u-boot-main,...u-boot-main是目标all的一个依赖。

%.o: %.c prepare scripts FORCE
    $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)

    @echo ************** $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@) *****************
把工程清理，重新编译，
为什么没有看到 @echo ************** $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@) ***************** 执行 ？？

正点原子

帮顶

1547674987

你到每个libs-y 包含的目录去看build-in.o.cmd就知道了，就是把一个或则多个.o 链接成一个build-in.o，如fs目录下build-in.o.cmd:  cmd_fs/built-in.o :=  arm-linux-gnueabihf-ld.bfd     -r -o fs/built-in.o fs/fs.o fs/ext4/built-in.o fs/fat/built-in.o