Linux 下的 CONFIG_OF 选项

最新推荐文章于 2025-06-22 21:00:00 发布
转载 最新推荐文章于 2025-06-22 21:00:00 发布 · 6.2k 阅读 · 1

本文深入探讨了设备树(DT)在Linux内核中的应用，解释了Open Firmware及其与设备树之间的关系，以及如何通过设备树进行设备数据交互。

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转载至：http://stackoverflow.com/questions/27978709/whats-the-config-of-in-linux

Open Firmware. This was invented long time ago when Apple was producing laptops based on PowerPC CPUs. Openfirmware provides a good description of the devices connected to the platform. In Linux kernel the part that works with device data is called Device Tree (DT). More details in the Usage model.

注：是和设备树相关的选项。

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分析代码：################################################################################ # # Linux kernel target # ################################################################################ LINUX_VERSION = $(call qstrip,$(BR2_LINUX_KERNEL_VERSION)) LINUX_LICENSE = GPLv2 LINUX_LICENSE_FILES = COPYING # Compute LINUX_SOURCE and LINUX_SITE from the configuration ifeq ($(BR2_LINUX_KERNEL_CUSTOM_TARBALL),y) LINUX_TARBALL = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION)) LINUX_SITE = $(patsubst %/,%,$(dir $(LINUX_TARBALL))) LINUX_SOURCE = $(notdir $(LINUX_TARBALL)) BR_NO_CHECK_HASH_FOR += $(LINUX_SOURCE) else ifeq ($(BR2_LINUX_KERNEL_CUSTOM_LOCAL),y) LINUX_SITE = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_LOCAL_PATH)) LINUX_SITE_METHOD = local else ifeq ($(BR2_LINUX_KERNEL_CUSTOM_GIT),y) LINUX_SITE = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_REPO_URL)) LINUX_SITE_METHOD = git else ifeq ($(BR2_LINUX_KERNEL_CUSTOM_HG),y) LINUX_SITE = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_REPO_URL)) LINUX_SITE_METHOD = hg else LINUX_SOURCE = linux-$(LINUX_VERSION).tar.xz ifeq ($(BR2_LINUX_KERNEL_CUSTOM_VERSION),y) BR_NO_CHECK_HASH_FOR += $(LINUX_SOURCE) endif ifeq ($(BR2_LINUX_KERNEL_SAME_AS_HEADERS)$(BR2_KERNEL_HEADERS_VERSION),yy) BR_NO_CHECK_HASH_FOR += $(LINUX_SOURCE) endif # In X.Y.Z, get X and Y. We replace dots and dashes by spaces in order # to use the $(word) function. We support versions such as 4.0, 3.1, # 2.6.32, 2.6.32-rc1, 3.0-rc6, etc. ifeq ($(findstring x2.6.,x$(LINUX_VERSION)),x2.6.) LINUX_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/v2.6 else ifeq ($(findstring x3.,x$(LINUX_VERSION)),x3.) LINUX_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/v3.x else ifeq ($(findstring x4.,x$(LINUX_VERSION)),x4.) LINUX_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/v4.x endif # release candidates are in testing/ subdir ifneq ($(findstring -rc,$(LINUX_VERSION)),) LINUX_SITE := $(LINUX_SITE)/testing endif # -rc endif LINUX_PATCHES = $(call qstrip,$(BR2_LINUX_KERNEL_PATCH)) # We rely on the generic package infrastructure to download and apply # remote patches (downloaded from ftp, http or https). For local # patches, we can't rely on that infrastructure, because there might # be directories in the patch list (unlike for other packages). LINUX_PATCH = $(filter ftp://% http://% https://%,$(LINUX_PATCHES)) LINUX_INSTALL_IMAGES = YES LINUX_DEPENDENCIES += host-kmod host-lzop host-lzma ifeq ($(BR2_LINUX_KERNEL_UBOOT_IMAGE),y) LINUX_DEPENDENCIES += host-uboot-tools endif LINUX_MAKE_FLAGS = \ HOSTCC="$(HOSTCC)" \ HOSTCFLAGS="$(HOSTCFLAGS)" \ ARCH=$(KERNEL_ARCH) \ INSTALL_MOD_PATH=$(TARGET_DIR) \ CROSS_COMPILE="$(TARGET_CROSS)" \ DEPMOD=$(HOST_DIR)/sbin/depmod LINUX_MAKE_ENV = \ $(TARGET_MAKE_ENV) \ BR_BINARIES_DIR=$(BINARIES_DIR) # Get the real Linux version, which tells us where kernel modules are # going to be installed in the target filesystem. LINUX_VERSION_PROBED = `$(MAKE) $(LINUX_MAKE_FLAGS) -C $(LINUX_DIR) --no-print-directory -s kernelrelease 2>/dev/null` ifeq ($(BR2_LINUX_KERNEL_USE_INTREE_DTS),y) KERNEL_DTS_NAME = $(call qstrip,$(BR2_LINUX_KERNEL_INTREE_DTS_NAME)) else ifeq ($(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),y) # We keep only the .dts files, so that the user can specify both .dts # and .dtsi files in BR2_LINUX_KERNEL_CUSTOM_DTS_PATH. Both will be # copied to arch/<arch>/boot/dts, but only the .dts files will # actually be generated as .dtb. KERNEL_DTS_NAME = $(basename $(filter %.dts,$(notdir $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH))))) endif KERNEL_DTBS = $(addsuffix .dtb,$(KERNEL_DTS_NAME)) ifeq ($(BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM),y) LINUX_IMAGE_NAME = $(call qstrip,$(BR2_LINUX_KERNEL_IMAGE_NAME)) LINUX_TARGET_NAME = $(call qstrip,$(BR2_LINUX_KERNEL_IMAGE_TARGET_NAME)) ifeq ($(LINUX_IMAGE_NAME),) LINUX_IMAGE_NAME = $(LINUX_TARGET_NAME) endif else ifeq ($(BR2_LINUX_KERNEL_UIMAGE),y) LINUX_IMAGE_NAME = uImage else ifeq ($(BR2_LINUX_KERNEL_APPENDED_UIMAGE),y) LINUX_IMAGE_NAME = uImage else ifeq ($(BR2_LINUX_KERNEL_BZIMAGE),y) LINUX_IMAGE_NAME = bzImage else ifeq ($(BR2_LINUX_KERNEL_ZIMAGE),y) LINUX_IMAGE_NAME = zImage else ifeq ($(BR2_LINUX_KERNEL_ZIMAGE_EPAPR),y) LINUX_IMAGE_NAME = zImage.epapr else ifeq ($(BR2_LINUX_KERNEL_APPENDED_ZIMAGE),y) LINUX_IMAGE_NAME = zImage else ifeq ($(BR2_LINUX_KERNEL_CUIMAGE),y) LINUX_IMAGE_NAME = cuImage.$(KERNEL_DTS_NAME) else ifeq ($(BR2_LINUX_KERNEL_SIMPLEIMAGE),y) LINUX_IMAGE_NAME = simpleImage.$(KERNEL_DTS_NAME) else ifeq ($(BR2_LINUX_KERNEL_IMAGE),y) LINUX_IMAGE_NAME = Image else ifeq ($(BR2_LINUX_KERNEL_LINUX_BIN),y) LINUX_IMAGE_NAME = linux.bin else ifeq ($(BR2_LINUX_KERNEL_VMLINUX_BIN),y) LINUX_IMAGE_NAME = vmlinux.bin else ifeq ($(BR2_LINUX_KERNEL_VMLINUX),y) LINUX_IMAGE_NAME = vmlinux else ifeq ($(BR2_LINUX_KERNEL_VMLINUZ),y) LINUX_IMAGE_NAME = vmlinuz endif # The if-else blocks above are all the image types we know of, and all # come from a Kconfig choice, so we know we have LINUX_IMAGE_NAME set # to something LINUX_TARGET_NAME = $(LINUX_IMAGE_NAME) endif LINUX_KERNEL_UIMAGE_LOADADDR = $(call qstrip,$(BR2_LINUX_KERNEL_UIMAGE_LOADADDR)) ifneq ($(LINUX_KERNEL_UIMAGE_LOADADDR),) LINUX_MAKE_FLAGS += LOADADDR="$(LINUX_KERNEL_UIMAGE_LOADADDR)" endif # Compute the arch path, since i386 and x86_64 are in arch/x86 and not # in arch/$(KERNEL_ARCH). Even if the kernel creates symbolic links # for bzImage, arch/i386 and arch/x86_64 do not exist when copying the # defconfig file. ifeq ($(KERNEL_ARCH),i386) KERNEL_ARCH_PATH = $(LINUX_DIR)/arch/x86 else ifeq ($(KERNEL_ARCH),x86_64) KERNEL_ARCH_PATH = $(LINUX_DIR)/arch/x86 else KERNEL_ARCH_PATH = $(LINUX_DIR)/arch/$(KERNEL_ARCH) endif ifeq ($(BR2_LINUX_KERNEL_VMLINUX),y) LINUX_IMAGE_PATH = $(LINUX_DIR)/$(LINUX_IMAGE_NAME) else ifeq ($(BR2_LINUX_KERNEL_VMLINUZ),y) LINUX_IMAGE_PATH = $(LINUX_DIR)/$(LINUX_IMAGE_NAME) else LINUX_IMAGE_PATH = $(KERNEL_ARCH_PATH)/boot/$(LINUX_IMAGE_NAME) endif # BR2_LINUX_KERNEL_VMLINUX define LINUX_APPLY_LOCAL_PATCHES for p in $(filter-out ftp://% http://% https://%,$(LINUX_PATCHES)) ; do \ if test -d $$p ; then \ $(APPLY_PATCHES) $(@D) $$p \*.patch || exit 1 ; \ else \ $(APPLY_PATCHES) $(@D) `dirname $$p` `basename $$p` || exit 1; \ fi \ done endef LINUX_POST_PATCH_HOOKS += LINUX_APPLY_LOCAL_PATCHES ifeq ($(BR2_LINUX_KERNEL_USE_DEFCONFIG),y) KERNEL_SOURCE_CONFIG = $(KERNEL_ARCH_PATH)/configs/$(call qstrip,$(BR2_LINUX_KERNEL_DEFCONFIG))_defconfig else ifeq ($(BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG),y) KERNEL_SOURCE_CONFIG = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE)) endif LINUX_KCONFIG_FILE = $(KERNEL_SOURCE_CONFIG) LINUX_KCONFIG_FRAGMENT_FILES = $(call qstrip,$(BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES)) LINUX_KCONFIG_EDITORS = menuconfig xconfig gconfig nconfig LINUX_KCONFIG_OPTS = $(LINUX_MAKE_FLAGS) define LINUX_KCONFIG_FIXUP_CMDS $(if $(LINUX_NEEDS_MODULES), $(call KCONFIG_ENABLE_OPT,CONFIG_MODULES,$(@D)/.config)) $(if $(BR2_arm)$(BR2_armeb), $(call KCONFIG_ENABLE_OPT,CONFIG_AEABI,$(@D)/.config)) $(if $(BR2_TARGET_ROOTFS_CPIO), $(call KCONFIG_ENABLE_OPT,CONFIG_BLK_DEV_INITRD,$(@D)/.config)) # As the kernel gets compiled before root filesystems are # built, we create a fake cpio file. It'll be # replaced later by the real cpio archive, and the kernel will be # rebuilt using the linux-rebuild-with-initramfs target. $(if $(BR2_TARGET_ROOTFS_INITRAMFS), touch $(BINARIES_DIR)/rootfs.cpio $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_SOURCE,"$${BR_BINARIES_DIR}/rootfs.cpio",$(@D)/.config) $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_UID,0,$(@D)/.config) $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_GID,0,$(@D)/.config)) $(if $(BR2_ROOTFS_DEVICE_CREATION_STATIC),, $(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS_MOUNT,$(@D)/.config)) $(if $(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV), $(call KCONFIG_ENABLE_OPT,CONFIG_INOTIFY_USER,$(@D)/.config)) $(if $(BR2_PACKAGE_KTAP), $(call KCONFIG_ENABLE_OPT,CONFIG_DEBUG_FS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_ENABLE_DEFAULT_TRACERS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_PERF_EVENTS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_FUNCTION_TRACER,$(@D)/.config)) $(if $(BR2_PACKAGE_SYSTEMD), $(call KCONFIG_ENABLE_OPT,CONFIG_CGROUPS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_INOTIFY_USER,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_FHANDLE,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_AUTOFS4_FS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_TMPFS_POSIX_ACL,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_TMPFS_POSIX_XATTR,$(@D)/.config)) $(if $(BR2_PACKAGE_SMACK), $(call KCONFIG_ENABLE_OPT,CONFIG_SECURITY,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_SECURITY_SMACK,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_SECURITY_NETWORK,$(@D)/.config)) $(if $(BR2_PACKAGE_IPTABLES), $(call KCONFIG_ENABLE_OPT,CONFIG_IP_NF_IPTABLES,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_IP_NF_FILTER,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_NETFILTER,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_NETFILTER_XTABLES,$(@D)/.config)) $(if $(BR2_PACKAGE_XTABLES_ADDONS), $(call KCONFIG_ENABLE_OPT,CONFIG_NETFILTER_ADVANCED,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_NF_CONNTRACK,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_NF_CONNTRACK_MARK,$(@D)/.config)) $(if $(BR2_LINUX_KERNEL_APPENDED_DTB), $(call KCONFIG_ENABLE_OPT,CONFIG_ARM_APPENDED_DTB,$(@D)/.config)) endef ifeq ($(BR2_LINUX_KERNEL_DTS_SUPPORT),y) ifeq ($(BR2_LINUX_KERNEL_DTB_IS_SELF_BUILT),) define LINUX_BUILD_DTB $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(KERNEL_DTBS) endef define LINUX_INSTALL_DTB # dtbs moved from arch/<ARCH>/boot to arch/<ARCH>/boot/dts since 3.8-rc1 cp $(addprefix \ $(KERNEL_ARCH_PATH)/boot/$(if $(wildcard \ $(addprefix $(KERNEL_ARCH_PATH)/boot/dts/,$(KERNEL_DTBS))),dts/),$(KERNEL_DTBS)) \ $(BINARIES_DIR)/ endef define LINUX_INSTALL_DTB_TARGET # dtbs moved from arch/<ARCH>/boot to arch/<ARCH>/boot/dts since 3.8-rc1 cp $(addprefix \ $(KERNEL_ARCH_PATH)/boot/$(if $(wildcard \ $(addprefix $(KERNEL_ARCH_PATH)/boot/dts/,$(KERNEL_DTBS))),dts/),$(KERNEL_DTBS)) \ $(TARGET_DIR)/boot/ endef endif endif ifeq ($(BR2_LINUX_KERNEL_APPENDED_DTB),y) # dtbs moved from arch/$ARCH/boot to arch/$ARCH/boot/dts since 3.8-rc1 define LINUX_APPEND_DTB if [ -e $(KERNEL_ARCH_PATH)/boot/$(KERNEL_DTS_NAME).dtb ]; then \ cat $(KERNEL_ARCH_PATH)/boot/$(KERNEL_DTS_NAME).dtb; \ else \ cat $(KERNEL_ARCH_PATH)/boot/dts/$(KERNEL_DTS_NAME).dtb; \ fi >> $(KERNEL_ARCH_PATH)/boot/zImage endef ifeq ($(BR2_LINUX_KERNEL_APPENDED_UIMAGE),y) # We need to generate a new u-boot image that takes into # account the extra-size added by the device tree at the end # of the image. To do so, we first need to retrieve both load # address and entry point for the kernel from the already # generate uboot image before using mkimage -l. LINUX_APPEND_DTB += $(sep) MKIMAGE_ARGS=`$(MKIMAGE) -l $(LINUX_IMAGE_PATH) |\ sed -n -e 's/Image Name:[ ]*\(.*\)/-n \1/p' -e 's/Load Address:/-a/p' -e 's/Entry Point:/-e/p'`; \ $(MKIMAGE) -A $(MKIMAGE_ARCH) -O linux \ -T kernel -C none $${MKIMAGE_ARGS} \ -d $(KERNEL_ARCH_PATH)/boot/zImage $(LINUX_IMAGE_PATH); endif endif # Compilation. We make sure the kernel gets rebuilt when the # configuration has changed. define LINUX_BUILD_CMDS $(if $(BR2_LINUX_KERNEL_USE_CUSTOM_DTS), cp $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)) $(KERNEL_ARCH_PATH)/boot/dts/) $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_TARGET_NAME) @if grep -q "CONFIG_MODULES=y" $(@D)/.config; then \ $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) modules ; \ fi $(LINUX_BUILD_DTB) $(LINUX_APPEND_DTB) endef ifeq ($(BR2_LINUX_KERNEL_INSTALL_TARGET),y) define LINUX_INSTALL_KERNEL_IMAGE_TO_TARGET install -m 0644 -D $(LINUX_IMAGE_PATH) $(TARGET_DIR)/boot/$(LINUX_IMAGE_NAME) $(LINUX_INSTALL_DTB_TARGET) endef endif define LINUX_INSTALL_HOST_TOOLS # Installing dtc (device tree compiler) as host tool, if selected if grep -q "CONFIG_DTC=y" $(@D)/.config; then \ $(INSTALL) -D -m 0755 $(@D)/scripts/dtc/dtc $(HOST_DIR)/usr/bin/linux-dtc ; \ fi endef define LINUX_INSTALL_IMAGES_CMDS cp $(LINUX_IMAGE_PATH) $(BINARIES_DIR) $(LINUX_INSTALL_DTB) endef define LINUX_INSTALL_TARGET_CMDS $(LINUX_INSTALL_KERNEL_IMAGE_TO_TARGET) # Install modules and remove symbolic links pointing to build # directories, not relevant on the target @if grep -q "CONFIG_MODULES=y" $(@D)/.config; then \ $(LINUX_MAKE_ENV) $(MAKE1) $(LINUX_MAKE_FLAGS) -C $(@D) modules_install; \ rm -f $(TARGET_DIR)/lib/modules/$(LINUX_VERSION_PROBED)/build ; \ rm -f $(TARGET_DIR)/lib/modules/$(LINUX_VERSION_PROBED)/source ; \ fi $(LINUX_INSTALL_HOST_TOOLS) endef # Include all our extensions and tools definitions. # # Note: our package infrastructure uses the full-path of the last-scanned # Makefile to determine what package we're currently defining, using the # last directory component in the path. As such, including other Makefile, # like below, before we call one of the *-package macro is usally not # working. # However, since the files we include here are in the same directory as # the current Makefile, we are OK. But this is a hard requirement: files # included here *must* be in the same directory! include $(sort $(wildcard linux/linux-ext-*.mk)) include $(sort $(wildcard linux/linux-tool-*.mk)) LINUX_PATCH_DEPENDENCIES += $(foreach ext,$(LINUX_EXTENSIONS),\ $(if $(BR2_LINUX_KERNEL_EXT_$(call UPPERCASE,$(ext))),$(ext))) LINUX_PRE_PATCH_HOOKS += $(foreach ext,$(LINUX_EXTENSIONS),\ $(if $(BR2_LINUX_KERNEL_EXT_$(call UPPERCASE,$(ext))),\ $(call UPPERCASE,$(ext))_PREPARE_KERNEL)) # Install Linux kernel tools in the staging directory since some tools # may install shared libraries and headers (e.g. cpupower). The kernel # image is NOT installed in the staging directory. LINUX_INSTALL_STAGING = YES LINUX_DEPENDENCIES += $(foreach tool,$(LINUX_TOOLS),\ $(if $(BR2_LINUX_KERNEL_TOOL_$(call UPPERCASE,$(tool))),\ $($(call UPPERCASE,$(tool))_DEPENDENCIES))) LINUX_POST_BUILD_HOOKS += $(foreach tool,$(LINUX_TOOLS),\ $(if $(BR2_LINUX_KERNEL_TOOL_$(call UPPERCASE,$(tool))),\ $(call UPPERCASE,$(tool))_BUILD_CMDS)) LINUX_POST_INSTALL_STAGING_HOOKS += $(foreach tool,$(LINUX_TOOLS),\ $(if $(BR2_LINUX_KERNEL_TOOL_$(call UPPERCASE,$(tool))),\ $(call UPPERCASE,$(tool))_INSTALL_STAGING_CMDS)) LINUX_POST_INSTALL_TARGET_HOOKS += $(foreach tool,$(LINUX_TOOLS),\ $(if $(BR2_LINUX_KERNEL_TOOL_$(call UPPERCASE,$(tool))),\ $(call UPPERCASE,$(tool))_INSTALL_TARGET_CMDS)) # Checks to give errors that the user can understand ifeq ($(BR_BUILDING),y) ifeq ($(BR2_LINUX_KERNEL_USE_DEFCONFIG),y) ifeq ($(call qstrip,$(BR2_LINUX_KERNEL_DEFCONFIG)),) $(error No kernel defconfig name specified, check your BR2_LINUX_KERNEL_DEFCONFIG setting) endif endif ifeq ($(BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG),y) ifeq ($(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE)),) $(error No kernel configuration file specified, check your BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE setting) endif endif ifeq ($(BR2_LINUX_KERNEL_DTS_SUPPORT)$(KERNEL_DTS_NAME),y) $(error No kernel device tree source specified, check your \ BR2_LINUX_KERNEL_USE_INTREE_DTS / BR2_LINUX_KERNEL_USE_CUSTOM_DTS settings) endif ifeq ($(BR2_LINUX_KERNEL_APPENDED_DTB),y) ifneq ($(words $(KERNEL_DTS_NAME)),1) $(error Kernel with appended device tree needs exactly one DTS source. \ Check BR2_LINUX_KERNEL_INTREE_DTS_NAME or BR2_LINUX_KERNEL_CUSTOM_DTS_PATH.) endif endif endif # BR_BUILDING $(eval $(kconfig-package)) # Support for rebuilding the kernel after the cpio archive has # been generated in $(BINARIES_DIR)/rootfs.cpio. $(LINUX_DIR)/.stamp_initramfs_rebuilt: $(LINUX_DIR)/.stamp_target_installed $(LINUX_DIR)/.stamp_images_installed $(BINARIES_DIR)/rootfs.cpio @$(call MESSAGE,"Rebuilding kernel with initramfs") # Build the kernel. $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_TARGET_NAME) $(LINUX_APPEND_DTB) # Copy the kernel image to its final destination cp $(LINUX_IMAGE_PATH) $(BINARIES_DIR) # If there is a .ub file copy it to the final destination test ! -f $(LINUX_IMAGE_PATH).ub || cp $(LINUX_IMAGE_PATH).ub $(BINARIES_DIR) $(Q)touch $@ # The initramfs building code must make sure this target gets called # after it generated the initramfs list of files. linux-rebuild-with-initramfs: $(LINUX_DIR)/.stamp_initramfs_rebuilt
最新发布
08-13
<think>我们正在分析一个Linux内核的Makefile代码片段。由于用户没有提供具体的Makefile代码，我无法直接分析。但是，我可以提供一个通用的分析框架，并假设一个典型的内核Makefile片段作为示例。 假设我们有以下的内核Makefile片段（取自引用[3]的启发）： ``` obj-$(CONFIG_EXT2_FS) += ext2.o ext2-y := balloc.o dir.o file.o ialloc.o inode.o ioctl.o namei.o super.o symlink.o ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o ext2-$(CONFIG_EXT2_FS_POSIX_ACL) += acl.o ext2-$(CONFIG_EXT2_FS_SECURITY) += xattr_security.o ``` 现在，我将按照这个示例片段进行解释。 在Linux内核的构建系统中，Makefile用于根据内核配置（由Kconfig生成，存储在.config文件中）来决定编译哪些对象文件（.o）并将它们链接成内核模块或内置到内核中。 下面逐行解释： 1. `obj-$(CONFIG_EXT2_FS) += ext2.o` 这行表示：如果配置选项`CONFIG_EXT2_FS`被设置为`y`（编译进内核）或`m`（编译成模块），那么变量`obj-y`或`obj-m`就会包含`ext2.o`。也就是说，根据配置，`ext2.o`要么被编译进内核，要么被编译成模块，或者不编译（如果配置为`n`）。 2. `ext2-y := balloc.o dir.o file.o ialloc.o inode.o ioctl.o namei.o super.o symlink.o` 这里定义了`ext2-y`变量，它列出了构建`ext2.o`所需的目标文件。这些文件会被链接到一起形成`ext2.o`（如果配置为内置）或者用于构建模块（如果配置为模块）。注意，这里使用`ext2-y`而不是`ext2-objs`，但在新版本内核中，两者都可以，通常使用`ext2-y`。 3. `ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o` 这行表示：如果配置选项`CONFIG_EXT2_FS_XATTR`被设置，那么就会在`ext2-y`（或`ext2-m`，取决于`CONFIG_EXT2_FS`）中追加这三个文件。注意，这里使用了相同的变量扩展机制，所以如果`CONFIG_EXT2_FS_XATTR`为`y`或`m`，则追加这些文件。但是，由于`ext2.o`本身要么是y要么是m，所以这里追加到`ext2-y`（或`ext2-m`）是合理的。实际上，在内核构建系统中，当模块被配置为m时，`ext2-y`会被视为`ext2-m`，但通常我们使用`ext2-y`来统一表示。 4. 接下来的两行也是类似的，根据不同的配置选项追加不同的文件。 总结：这个Makefile片段用于构建ext2文件系统的内核对象（模块或内置）。它根据内核配置选项，决定哪些源文件需要被编译并链接到ext2对象中。 注意：内核的Makefile使用了很多特定的变量和规则，这些规则由内核的顶层Makefile定义。因此，在分析内核Makefile时，需要了解内核构建系统的基本知识。 现在，如果用户提供了具体的Makefile代码片段，我们可以进行更具体的分析。如果用户没有提供，我们可以建议用户提供具体的代码片段。 根据引用[3]，我们还知道在Makefile中可以使用`$(shell ...)`来执行命令替换。但在内核的Makefile中，通常避免使用shell命令，因为内核构建系统强调可移植性和效率。不过，在内核的Makefile中，有时也会使用`$(shell)`来执行一些必要的命令（例如获取内核版本等）。 生成相关问题： 1. Linux内核构建系统中，Kconfig和Makefile的关系是什么？ 2. 在内核Makefile中，obj-y和obj-m有什么区别？ 3. 如何在内核Makefile中添加一个新的内核模块？ 4. 内核Makefile中常用的变量和函数有哪些？ 5. 如何调试内核Makefile的构建过程？ 注意：由于用户没有提供具体的Makefile代码，上述分析是基于一个假设的典型片段。如果用户提供了具体的代码，分析将基于实际代码进行。</think>以下是对Linux内核Makefile代码片段的功能和结构分析，结合内核构建系统的特点： ### 1. **基本功能解析** ```makefile obj-$(CONFIG_EXT2_FS) += ext2.o ext2-y := balloc.o dir.o file.o ialloc.o inode.o ioctl.o namei.o super.o symlink.o ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o ext2-$(CONFIG_EXT2_FS_POSIX_ACL) += acl.o ext2-$(CONFIG_EXT2_FS_SECURITY) += xattr_security.o ``` #### (1) **条件编译控制** - `obj-$(CONFIG_EXT2_FS)`：根据内核配置选项`CONFIG_EXT2_FS`的值决定编译行为： - 若`=y`：将ext2文件系统编译进内核镜像 - 若`=m`：编译成可加载模块 - 若未设置：不编译 - 语法`$( )`实现**变量替换**，这是Makefile的核心机制[^3] #### (2) **模块化组件管理** - `ext2-y`：定义基础必需对象文件（如`balloc.o`, `dir.o`等） - 条件追加： ```makefile ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o ... # 扩展属性支持 ext2-$(CONFIG_EXT2_FS_POSIX_ACL) += acl.o # POSIX ACL支持 ``` 根据配置动态添加功能组件 #### (3) **自动依赖解析** - 隐含规则自动处理`.c`→`.o`编译： ```makefile # 无需显式写出，由内核构建系统实现 balloc.o: balloc.c $(CC) -c $(CFLAGS) $< -o $@ ``` ### 2. **内核构建系统特点** - **独立API**：不使用用户空间库（如`printf`），完全依赖内核头文件和API[^1] - **内存管理**：通过`slab`分配器高效管理对象（如`mm_struct`）[^2] - **进程隔离**：每个组件独立编译，避免地址空间污染[^2] - **信号处理**：`Ctrl+C`（SIGINT）可中断长时间编译[^4] ### 3. **结构层次** ```mermaid graph TD A[顶层Makefile] --> B[arch/*/Makefile] B --> C[fs/Makefile] C --> D[fs/ext2/Makefile] D --> E{CONFIG_EXT2_FS} E -->|y/m| F[ext2-y对象文件] E -->|n| G[跳过编译] F --> H[链接为ext2.o] ``` ### 4. **关键机制** - **配置驱动**：通过`.config`文件生成`CONFIG_*`宏 - **递归构建**：`make -C $(KDIR) M=$(PWD)`调用内核构建系统 - **版本控制**：`$(shell uname -r)`获取内核版本[^3] - **安全编译**：`-Werror`将警告视为错误
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