OpenWrt kernel install分析(2)

一. 前言

接下来分析make -C image compile install TARGET_BUILD=。

二. Makefile分析

  1. 命令首先运行target/linux/mediatek/image/Makefile,该文件内容如下:

    target/linux/mediatek/image/Makefile:
    include $(TOPDIR)/rules.mk
    include $(INCLUDE_DIR)/image.mk

    ......

    build signed fit

    define Build/fit-sign
    $(TOPDIR)/scripts/mkits.sh
    -D $(DEVICE_NAME)
    -o $@.its
    -k $@
    $(if (word 2,(1)),-d (word 2,(1))) -C (word 1,(1))
    -a $(KERNEL_LOADADDR)
    -e $(if (KERNEL_ENTRY),(KERNEL_ENTRY),$(KERNEL_LOADADDR))
    -c $(if (DEVICE_DTS_CONFIG),(DEVICE_DTS_CONFIG),"config-1")
    -A $(LINUX_KARCH)
    -v $(LINUX_VERSION)
    -s (KDIR)/(DEVICE_NAME)-u-boot-script
    $(if $(FIT_KEY_NAME),-S $(FIT_KEY_NAME))
    $(if $(FW_AR_VER),-r (FW_AR_VER)) PATH=(LINUX_DIR)/scripts/dtc:$(PATH) mkimage
    -f $@.its
    $(if $(FIT_KEY_DIR),-k $(FIT_KEY_DIR))
    -r
    $@.new
    @mv $@.new $@
    endef

    default all platform image(fit) build

    define Device/Default
    PROFILES = Default $$(DEVICE_NAME)
    KERNEL_NAME := Image
    KERNEL = kernel-bin | lzma |
    fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb
    KERNEL_INITRAMFS = kernel-bin | lzma |
    fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb
    FILESYSTEMS := squashfs
    DEVICE_DTS_DIR := $(DTS_DIR)
    IMAGES := sysupgrade.bin
    IMAGE/sysupgrade.bin := append-kernel | pad-to 128k | append-rootfs |
    pad-rootfs | append-metadata
    FIT_KEY_DIR :=
    FIT_KEY_NAME :=
    endef

    include $(SUBTARGET).mk

    define Image/Build
    (call Image/Build/(1),$(1))
    endef

    $(eval $(call BuildImage))

BuildImage在include/image.mk中定义,install目标在里面,代码如下:

include/image.mk:
define BuildImage

......
  download:
  prepare:
  compile:
  clean:
  image_prepare:

  ifeq ($(IB),)
    .PHONY: download prepare compile clean image_prepare kernel_prepare install install-images
    compile:
		$(call Build/Compile)

    clean:
		$(call Build/Clean)

    image_prepare: compile
		mkdir -p $(BIN_DIR) $(KDIR)/tmp
		rm -rf $(BUILD_DIR)/json_info_files
		$(call Image/Prepare)

  else
    image_prepare:
		mkdir -p $(BIN_DIR) $(KDIR)/tmp
  endif

  kernel_prepare: image_prepare
	$(call Image/Build/targz)
	$(call Image/Build/cpiogz)
	$(call Image/BuildKernel)
	$(if $(CONFIG_TARGET_ROOTFS_INITRAMFS),$(if $(IB),,$(call Image/BuildKernel/Initramfs)))
	$(call Image/InstallKernel)

  $(foreach device,$(TARGET_DEVICES),$(call Device,$(device)))

  install-images: kernel_prepare $(foreach fs,$(filter-out $(if $(UBIFS_OPTS),,ubifs),$(TARGET_FILESYSTEMS) $(fs-subtypes-y)),$(KDIR)/root.$(fs))
	$(foreach fs,$(TARGET_FILESYSTEMS),
		$(call Image/Build,$(fs))
	)

  install: install-images
	$(call Image/Manifest)

endef

由上可知,install依赖于install-images,install-images依赖于kernel_prepare,kernel_prepare依赖于image_prepare,由于IB未定义,所以image_prepare定义如下:

compile:
		$(call Build/Compile)

clean:
		$(call Build/Clean)

image_prepare: compile
		mkdir -p $(BIN_DIR) $(KDIR)/tmp
		rm -rf $(BUILD_DIR)/json_info_files
		$(call Image/Prepare)

image_prepare依赖于compile,这里,Build/Compile并未定义,所以什么都不干

注意:image_prepare在另一处也有定义,如下:

ifndef IB
define Device/Build/dtb
  ifndef BUILD_DTS_$(1)
  BUILD_DTS_$(1) := 1
  $(KDIR)/image-$(1).dtb: FORCE
	$(call Image/BuildDTB,$(strip $(2))/$(strip $(3)).dts,$$@)

  image_prepare: $(KDIR)/image-$(1).dtb
  endif

endef
endif

这里在执行完上面compile依赖,接下来会完成(KDIR)/image-(1).dtb这个依赖,也就是生成设备树文件。

这种有两个相同目标的执行过程,下面用一个简单案例解释,如下:

act1:
        @echo "act1"

act2:
        @echo "act2"

target:act1

target:act2
        @echo "target finish"

all: target
        @echo "all finish"

这里有两个target目标,分别依赖act1和act2,注意,一个target是有执行动作的,一个没有,这里先执行act2依赖,再act1依赖,执行结果如下:

act2
act1
target finish
all finish

回到分析,

ifndef IB
define Device/Build/dtb
  ifndef BUILD_DTS_$(1)
  BUILD_DTS_$(1) := 1
  $(KDIR)/image-$(1).dtb: FORCE
	$(call Image/BuildDTB,$(strip $(2))/$(strip $(3)).dts,$$@)

  image_prepare: $(KDIR)/image-$(1).dtb
  endif

endef
endif

(KDIR)/image-(1).dtb也是一个目标,动作为(call Image/BuildDTB,(strip (2))/(strip (3)).dts,$@),Image/BuildDTB定义如下,

define Image/BuildDTB
	$(TARGET_CROSS)cpp -nostdinc -x assembler-with-cpp \
		-I$(DTS_DIR) \
		-I$(DTS_DIR)/include \
		-I$(LINUX_DIR)/include/ \
		-undef -D__DTS__ $(3) \
		-o $(2).tmp $(1)
	$(LINUX_DIR)/scripts/dtc/dtc -O dtb \
		-i$(dir $(1)) $(DTC_FLAGS) $(4) \
		-o $(2) $(2).tmp
	$(RM) $(2).tmp
endef

完整命令展开如下:

aarch64-openwrt-linux-musl-cpp -nostdinc -x assembler-with-cpp -I/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts -I/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts/include -I/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/include/ -undef -D__DTS__  -o /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/image-mt7981-spim-nor-rfb.dtb.tmp /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts/mediatek/mt7981-spim-nor-rfb.dts
aarch64-openwrt-linux-musl-cpp -nostdinc -x assembler-with-cpp -I/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts -I/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts/include -I/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/include/ -undef -D__DTS__ -o /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/image-mt7981-spim-nor-rfb.dtb.tmp /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts/mediatek/mt7981-spim-nor-rfb.dts
/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/scripts/dtc/dtc -O dtb -i/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/arch/arm64/boot/dts/mediatek/ -Wno-unit_address_vs_reg -Wno-simple_bus_reg -Wno-unit_address_format -Wno-pci_bridge -Wno-pci_device_bus_num -Wno-pci_device_reg -Wno-avoid_unnecessary_addr_size -Wno-alias_paths -Wno-graph_child_address -Wno-graph_port -Wno-unique_unit_address  -o /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/image-mt7981-spim-nor-rfb.dtb /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/image-mt7981-spim-nor-rfb.dtb.tmp

注意:

Device/Build/dtb是由下面代码展开得到的:

$(foreach device,$(TARGET_DEVICES),$(call Device,$(device)))

TARGET_DEVICES定义在target/linux/mediatek/image/mt7981.mk 中,可以如下:

openwrt# grep -rn "TARGET_DEVICES" target/linux/mediatek/image/mt7981.mk 
10:TARGET_DEVICES += mt7981-spim-nor-rfb
27:TARGET_DEVICES += mt7981-spim-nand-2500wan-gmac2
44:TARGET_DEVICES += mt7981-spim-nand-rfb
61:TARGET_DEVICES += mt7981-spim-nand-gsw
74:TARGET_DEVICES += mt7981-emmc-rfb
87:TARGET_DEVICES += mt7981-sd-rfb
104:TARGET_DEVICES += mt7981-snfi-nand-2500wan-p5
113:TARGET_DEVICES += mt7981-fpga-spim-nor
130:TARGET_DEVICES += mt7981-fpga-snfi-nand
147:TARGET_DEVICES += mt7981-fpga-spim-nand
160:TARGET_DEVICES += mt7981-fpga-emmc
173:TARGET_DEVICES += mt7981-fpga-sd

Device的定义如下:

define Device
  $(call Device/InitProfile,$(1))
  $(call Device/Init,$(1))
  $(call Device/Default,$(1))
  $(call Device/$(1),$(1))
  $(call Device/Check,$(1))
  $(call Device/$(if $(DUMP),Dump,Build),$(1))

endef

Device/Default定义在target/linux/mediatek/image/Makefile,内容如下:

define Device/Default
  PROFILES = Default $$(DEVICE_NAME)
  KERNEL_NAME := Image
  KERNEL = kernel-bin | lzma | \
	fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb
  KERNEL_INITRAMFS = kernel-bin | lzma | \
	fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb
  FILESYSTEMS := squashfs
  DEVICE_DTS_DIR := $(DTS_DIR)
  IMAGES := sysupgrade.bin
  IMAGE/sysupgrade.bin := append-kernel | pad-to 128k | append-rootfs | \
	pad-rootfs | append-metadata
  FIT_KEY_DIR :=
  FIT_KEY_NAME :=
endef

Device/(1):由于(1)=mt7981-spim-nor-rfb,表示Device/mt7981-spim-nor-rfb,定义在target/linux/mediatek/image/mt7981.mk,内容如下:

define Device/mt7981-spim-nor-rfb
  DEVICE_VENDOR := MediaTek
  DEVICE_MODEL := mt7981-spim-nor-rfb
  DEVICE_DTS := mt7981-spim-nor-rfb
  DEVICE_DTS_DIR := $(DTS_DIR)/mediatek
  SUPPORTED_DEVICES := mediatek,mt7981-spim-nor-rfb
endef
TARGET_DEVICES += mt7981-spim-nor-rfb

由于DUMP未定义,(call Device/(if (DUMP),Dump,Build),(1))为Device/Build。

  1. Device/Build展开如下

    define Device/Build

    (eval $$(foreach image,$$(IMAGES), \ $$(foreach fs,$$(filter $(TARGET_FILESYSTEMS),$$(FILESYSTEMS)), \ $$(call Device/Build/per-device-fs,$$(fs),$$(image),$(1))))) $(if $(CONFIG_TARGET_ROOTFS_INITRAMFS),$(call Device/Build/initramfs,$(1))) $(call Device/Build/kernel,$(1),$$(filter $(TARGET_FILESYSTEMS),$$(FILESYSTEMS))) $$(eval $$(foreach compile,$$(COMPILE), \ $$(call Device/Build/compile,$$(compile),$(1)))) $$(eval $$(foreach image,$$(IMAGES), \ $$(foreach fs,$$(filter $(TARGET_FILESYSTEMS),$$(FILESYSTEMS)), \ $$(call Device/Build/image,$$(fs),$$(image),$(1))))) $$(eval $$(foreach artifact,$$(ARTIFACTS), \ $$(call Device/Build/artifact,$$(artifact)))) endef

    define split_args
    $(foreach data,
    (subst |,(space),
    $(subst (space),^,(1))),
    $(call (2),(strip (subst ^,(space),$(data)))))
    endef

    define build_cmd
    $(if (Build/(word 1,(1))),,(error Missing Build/(word 1,(1))))
    (call Build/(word 1,(1)),(wordlist 2,$(words (1)),(1)))

    endef

    define concat_cmd
    (call split_args,(1),build_cmd)
    endef

    ifndef IB
    define Device/Build/initramfs
    (call Device/Export,(KDIR)/tmp/$$(KERNEL_INITRAMFS_IMAGE),$(1))

    (_TARGET): $$(if $$(KERNEL_INITRAMFS),$(BIN_DIR)/$$(KERNEL_INITRAMFS_IMAGE) \ $$(if $$(CONFIG_JSON_OVERVIEW_IMAGE_INFO), $(BUILD_DIR)/json_info_files/$$(KERNEL_INITRAMFS_IMAGE).json,)) $(KDIR)/$$(KERNEL_INITRAMFS_NAME):: image_prepare $(BIN_DIR)/$$(KERNEL_INITRAMFS_IMAGE): $(KDIR)/tmp/$$(KERNEL_INITRAMFS_IMAGE) cp $$^ $$@ $(KDIR)/tmp/$$(KERNEL_INITRAMFS_IMAGE): $(KDIR)/$$(KERNEL_INITRAMFS_NAME) $(CURDIR)/Makefile $$(KERNEL_DEPENDS) image_prepare @rm -f $$@ $$(call concat_cmd,$$(KERNEL_INITRAMFS)) ...... endef endif

         rm -f /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin
         cp /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/Image-initramfs /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin
    
         /home/work/openwrt/staging_dir/host/bin/lzma e /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin -lc1 -lp2 -pb2  /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin.new
         @mv /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin.new /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin
    
         /home/work/openwrt/scripts/mkits.sh -D mt7981-spim-nor-rfb -o /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin.its -k /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin -d /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/image-mt7981-spim-nor-rfb.dtb -C lzma -a 0x48080000 -e 0x48080000  -c "config-1" -A arm64 -v 5.4.203 
         PATH=/home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.203/scripts/dtc:/home/work/openwrt/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/bin:/home/work/openwrt/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/bin:/home/work/openwrt/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/bin:/home/work/openwrt/staging_dir/host/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/work/openwrt/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/bin/ mkimage -f /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin.its /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin.new
         @mv /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin.new /home/work/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/tmp/openwrt-mediatek-mt7981-mt7981-spim-nor-rfb-initramfs-kernel.bin
    

(eval $$(foreach compile,$$(COMPILE), $$(call Device/Build/compile,$$(compile),$(1))))展开如下: Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-spim-nor-rfb))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-spim-nand-2500wan-gmac2))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-spim-nand-rfb))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-spim-nand-gsw))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-emmc-rfb))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-sd-rfb))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-snfi-nand-2500wan-p5))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-fpga-spim-nor))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-fpga-snfi-nand))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-fpga-spim-nand))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-fpga-emmc))) Makefile:91: $(eval $(foreach compile,$(COMPILE), $(call Device/Build/compile,$(compile),mt7981-fpga-sd))) 由于$(COMPILE)为空,所以这块执行没有效果。 接下来, $$(eval $$(foreach image,$$(IMAGES), \ $$(foreach fs,$$(filter $(TARGET_FILESYSTEMS),$$(FILESYSTEMS)), \ $$(call Device/Build/image,$$(fs),$$(image),$(1))))) 由于TARGET_FILESYSTEMS是要编译的镜像格式类型,如下: fs-types-$(CONFIG_TARGET_ROOTFS_SQUASHFS) += squashfs fs-types-$(CONFIG_TARGET_ROOTFS_JFFS2) += $(addprefix jffs2-,$(JFFS2_BLOCKSIZE)) fs-types-$(CONFIG_TARGET_ROOTFS_JFFS2_NAND) += $(addprefix jffs2-nand-,$(NAND_BLOCKSIZE)) fs-types-$(CONFIG_TARGET_ROOTFS_EXT4FS) += ext4 fs-types-$(CONFIG_TARGET_ROOTFS_UBIFS) += ubifs fs-subtypes-$(CONFIG_TARGET_ROOTFS_JFFS2) += $(addsuffix -raw,$(addprefix jffs2-,$(JFFS2_BLOCKSIZE))) TARGET_FILESYSTEMS := $(fs-types-y) 由于CONFIG_TARGET_ROOTFS_SQUASHFS等我都没选,所以,TARGET_FILESYSTEMS为空,这里也是不执行的。可以看出Device/Build/image的作用是生成不同文件系统的镜像。 接下来, $$(eval $$(foreach artifact,$$(ARTIFACTS), \ $$(call Device/Build/artifact,$$(artifact)))) 由于ARTIFACTS变量为空,所以,这里Device/Build/artifact什么也不干。 ### 三. 总结 这里需要注意的以下几点: 1. image_prepare有两个目标,有动作的这个目标做的事情很少,没有目标的依赖是用于编译设备树的,要非常注意。 2. 由于编译选项没选,Image/Build/targz,Image/Build/cpiogz这里什么也不做,Image/BuildKernel和Image/InstallKernel没有定义(可能是用于自定义的,这里没用到而已),这里什么也不做。 3. $(if $(CONFIG_TARGET_ROOTFS_INITRAMFS),$(if $(IB),,$(call Image/BuildKernel/Initramfs))),这里结果为$(call Image/BuildKernel/Initramfs),继续展开为$(call Image/Build/Initramfs),但是Image/Build/Initramfs未定义,所以这里什么也不干,也是用于自定义的。 4. $(foreach device,$(TARGET_DEVICES),$(call Device,$(device))),这里TARGET_DEVICES定义在mt7981.mk中,表示不同的镜像(spi-nor,spi-nand,emmc等等),Device宏里面要关注Device/Default和Device/Build,Device/Default定义在target/linux/mediatek/image/Makefile中,定义了一些镜像相关的变量,Device/Build中要关注$(if $(CONFIG_TARGET_ROOTFS_INITRAMFS),$(call Device/Build/initramfs,$(1))),结果是$(call Device/Build/initramfs,$(1)),重点要关注$$(call concat_cmd,$$(KERNEL_INITRAMFS))这里,这里面打包了最终的镜像(lzma压缩,its文件生成,mkimage都在这里执行)。

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