rk3588编译-uboot交叉编译-scripts/Makefile.build分析

https://blog.csdn.net/m0_37761102/article/details/121147426 (简单明了)
https://blog.csdn.net/metersun/article/details/52212842
https://zhuanlan.zhihu.com/p/362958145

# ==========================================================================
# Building
# ==========================================================================
#
# SPDX-License-Identifier:  GPL-2.0
#

# Modified for U-Boot
# 这里把obj变量赋值给src
prefix := tpl
src := $(patsubst $(prefix)/%,%,$(obj))
ifeq ($(obj),$(src))
prefix := spl
src := $(patsubst $(prefix)/%,%,$(obj))
ifeq ($(obj),$(src))
prefix := .
endif
endif

# Read auto.conf if it exists, otherwise ignore
# Modified for U-Boot
-include include/config/auto.conf
-include $(prefix)/include/autoconf.mk
include scripts/Makefile.uncmd_spl

include scripts/Kbuild.include

# The filename Kbuild has precedence over Makefile
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)

# 遍历obj变量指定的目录下的Makefile文件
include $(kbuild-file)

include scripts/Makefile.lib

ifndef obj
$(warning kbuild: Makefile.build is included improperly)
endif

# ===========================================================================

ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
lib-target := $(obj)/lib.a
endif

ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
builtin-target := $(obj)/built-in.o
endif

modorder-target := $(obj)/modules.order

# We keep a list of all modules in $(MODVERDIR)

# 默认的build目标
__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
     $(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
     $(subdir-ym) $(always)