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@cyysu 2017-10-17T06:41:22.000000Z 字数 13236 阅读 1322

Makefile-项目篇(五)

  • 时间：22017年10月17日
  • 作者：Kali
  • 邮箱：cyysu.github.io@gmail.com
  • 版本：3.0
  • 描述：Makefile-项目五，继Makefile项目篇四的Makefile

Makefile系列教程

实战项目

大多数知识点我已经在基础篇五里面讲解过了，在分析内核的Makefile时最好有一个源码分析工具，还有遇到问题先不要纠结，继续向下面看，然后在回来思考那个问题，问题可能就会换了一个角度。

  1. # To avoid any implicit rule to kick in, define an empty command
  2. $(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
  4. # If .config is newer than include/config/auto.conf, someone tinkered
  5. # with it and forgot to run make oldconfig.
  6. # if auto.conf.cmd is missing then we are probably in a cleaned tree so
  7. # we execute the config step to be sure to catch updated Kconfig files
  8. include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
  9. 	$(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
  10. else
  11. # external modules needs include/generated/autoconf.h and include/config/auto.conf
  12. # but do not care if they are up-to-date. Use auto.conf to trigger the test
  13. PHONY += include/config/auto.conf
  15. include/config/auto.conf:
  16.     $(Q)test -e include/generated/autoconf.h -a -e $@ || (     \
  17.     echo >&2;                           \
  18.     echo >&2 "  ERROR: Kernel configuration is invalid.";       \
  19.     echo >&2 "         include/generated/autoconf.h or $@ are missing.";\
  20.     echo >&2 "         Run 'make oldconfig && make prepare' on kernel src to fix it.";  \
  21.     echo >&2 ;                          \
  22.     /bin/false)
  24. endif # KBUILD_EXTMOD
  26. else
  27. # Dummy target needed, because used as prerequisite
  28. include/config/auto.conf: ;
  29. endif # $(dot-config)
  31. # The all: target is the default when no target is given on the
  32. # command line.
  33. # This allow a user to issue only 'make' to build a kernel including modules
  34. # Defaults to vmlinux, but the arch makefile usually adds further targets
  35. all: vmlinux
  37. # The arch Makefile can set ARCH_{CPP,A,C}FLAGS to override the default
  38. # values of the respective KBUILD_* variables
  39. ARCH_CPPFLAGS :=
  40. ARCH_AFLAGS :=
  41. ARCH_CFLAGS :=
  42. # 这个地方涉及到了 编译过程中的make -f ./scripts/Makefile.build obj=arch/x86/tools relocs
  43. include arch/$(SRCARCH)/Makefile
  45. # 这里的call函数，就是可以用后面的参数更新前面的变量
  46. KBUILD_CFLAGS   += $(call cc-option,-fno-delete-null-pointer-checks,)
  47. KBUILD_CFLAGS	+= $(call cc-disable-warning,maybe-uninitialized,)
  48. KBUILD_CFLAGS   += $(call cc-disable-warning,frame-address,)
  49. KBUILD_CFLAGS	+= $(call cc-disable-warning, format-truncation)
  50. KBUILD_CFLAGS   += $(call cc-disable-warning, format-overflow)
  51. KBUILD_CFLAGS	+= $(call cc-disable-warning, int-in-bool-context)
  53. ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
  54. KBUILD_CFLAGS   += -Os
  55. else
  56. ifdef CONFIG_PROFILE_ALL_BRANCHES
  57. KBUILD_CFLAGS   += -O2
  58. else
  59. KBUILD_CFLAGS   += -O2
  60. endif
  61. endif
  63. # Tell gcc to never replace conditional load with a non-conditional one
  64. KBUILD_CFLAGS   += $(call cc-option,--param=allow-store-data-races=0)
  66. # check for 'asm goto'
  67. ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
  68.     KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
  69.     KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
  70. endif
  72. ifdef CONFIG_READABLE_ASM
  73. # Disable optimizations that make assembler listings hard to read.
  74. # reorder blocks reorders the control in the function
  75. # ipa clone creates specialized cloned functions
  76. # partial inlining inlines only parts of functions
  77. KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \
  78.                  $(call cc-option,-fno-ipa-cp-clone,) \
  79.                  $(call cc-option,-fno-partial-inlining)
  80. endif
  82. ifneq ($(CONFIG_FRAME_WARN),0)
  83. KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
  84. endif
  86. # Handle stack protector mode.
  87. #
  88. # Since kbuild can potentially perform two passes (first with the old
  89. # .config values and then with updated .config values), we cannot error out
  90. # if a desired compiler option is unsupported. If we were to error, kbuild
  91. # could never get to the second pass and actually notice that we changed
  92. # the option to something that was supported.
  93. #
  94. # Additionally, we don't want to fallback and/or silently change which compiler
  95. # flags will be used, since that leads to producing kernels with different
  96. # security feature characteristics depending on the compiler used. ("But I
  97. # selected CC_STACKPROTECTOR_STRONG! Why did it build with _REGULAR?!")
  98. #
  99. # The middle ground is to warn here so that the failed option is obvious, but
  100. # to let the build fail with bad compiler flags so that we can't produce a
  101. # kernel when there is a CONFIG and compiler mismatch.
  102. #
  103. ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
  104.   stackp-flag := -fstack-protector
  105.   ifeq ($(call cc-option, $(stackp-flag)),)
  106.     $(warning Cannot use CONFIG_CC_STACKPROTECTOR_REGULAR: \
  107.              -fstack-protector not supported by compiler)
  108.   endif
  109. else
  110. ifdef CONFIG_CC_STACKPROTECTOR_STRONG
  111.   stackp-flag := -fstack-protector-strong
  112.   ifeq ($(call cc-option, $(stackp-flag)),)
  113.     $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
  114.           -fstack-protector-strong not supported by compiler)
  115.   endif
  116. else
  117.   # Force off for distro compilers that enable stack protector by default.
  118.   stackp-flag := $(call cc-option, -fno-stack-protector)
  119. endif
  120. endif
  121. KBUILD_CFLAGS += $(stackp-flag)
  123. ifeq ($(cc-name),clang)
  124. KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
  125. KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
  126. KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
  127. KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
  128. KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
  129. # Quiet clang warning: comparison of unsigned expression < 0 is always false
  130. KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
  131. # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
  132. # source of a reference will be _MergedGlobals and not on of the whitelisted names.
  133. # See modpost pattern 2
  134. KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
  135. KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
  136. else
  138. # These warnings generated too much noise in a regular build.
  139. # Use make W=1 to enable them (see scripts/Makefile.build)
  140. KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
  141. KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
  142. endif
  144. ifdef CONFIG_FRAME_POINTER
  145. KBUILD_CFLAGS   += -fno-omit-frame-pointer -fno-optimize-sibling-calls
  146. else
  147. # Some targets (ARM with Thumb2, for example), can't be built with frame
  148. # pointers.  For those, we don't have FUNCTION_TRACER automatically
  149. # select FRAME_POINTER.  However, FUNCTION_TRACER adds -pg, and this is
  150. # incompatible with -fomit-frame-pointer with current GCC, so we don't use
  151. # -fomit-frame-pointer with FUNCTION_TRACER.
  152. ifndef CONFIG_FUNCTION_TRACER
  153. KBUILD_CFLAGS   += -fomit-frame-pointer
  154. endif
  155. endif
  157. KBUILD_CFLAGS   += $(call cc-option, -fno-var-tracking-assignments)
  159. ifdef CONFIG_DEBUG_INFO
  160. ifdef CONFIG_DEBUG_INFO_SPLIT
  161. KBUILD_CFLAGS   += $(call cc-option, -gsplit-dwarf, -g)
  162. else
  163. KBUILD_CFLAGS	+= -g
  164. endif
  165. KBUILD_AFLAGS	+= -Wa,-gdwarf-2
  166. endif
  167. ifdef CONFIG_DEBUG_INFO_DWARF4
  168. KBUILD_CFLAGS	+= $(call cc-option, -gdwarf-4,)
  169. endif
  171. ifdef CONFIG_DEBUG_INFO_REDUCED
  172. KBUILD_CFLAGS   += $(call cc-option, -femit-struct-debug-baseonly) \
  173. 		   $(call cc-option,-fno-var-tracking)
  174. endif
  176. ifdef CONFIG_FUNCTION_TRACER
  177. ifndef CC_FLAGS_FTRACE
  178. CC_FLAGS_FTRACE := -pg
  179. endif
  180. export CC_FLAGS_FTRACE
  181. ifdef CONFIG_HAVE_FENTRY
  182. CC_USING_FENTRY := $(call cc-option, -mfentry -DCC_USING_FENTRY)
  183. endif
  184. KBUILD_CFLAGS	+= $(CC_FLAGS_FTRACE) $(CC_USING_FENTRY)
  185. KBUILD_AFLAGS	+= $(CC_USING_FENTRY)
  186. ifdef CONFIG_DYNAMIC_FTRACE
  187.     ifdef CONFIG_HAVE_C_RECORDMCOUNT
  188.         BUILD_C_RECORDMCOUNT := y
  189.         export BUILD_C_RECORDMCOUNT
  190.     endif
  191. endif
  192. endif
  194. # We trigger additional mismatches with less inlining
  195. ifdef CONFIG_DEBUG_SECTION_MISMATCH
  196. KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
  197. endif
  199. # arch Makefile may override CC so keep this after arch Makefile is included
  200. NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
  201. CHECKFLAGS     += $(NOSTDINC_FLAGS)
  203. # warn about C99 declaration after statement
  204. KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
  206. # disable pointer signed / unsigned warnings in gcc 4.0
  207. KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign)
  209. # disable invalid "can't wrap" optimizations for signed / pointers
  210. KBUILD_CFLAGS   += $(call cc-option,-fno-strict-overflow)
  212. # conserve stack if available
  213. KBUILD_CFLAGS   += $(call cc-option,-fconserve-stack)
  215. # disallow errors like 'EXPORT_GPL(foo);' with missing header
  216. KBUILD_CFLAGS   += $(call cc-option,-Werror=implicit-int)
  218. # require functions to have arguments in prototypes, not empty 'int foo()'
  219. KBUILD_CFLAGS   += $(call cc-option,-Werror=strict-prototypes)
  221. # Prohibit date/time macros, which would make the build non-deterministic
  222. KBUILD_CFLAGS   += $(call cc-option,-Werror=date-time)
  224. # use the deterministic mode of AR if available
  225. KBUILD_ARFLAGS := $(call ar-option,D)
  227. include scripts/Makefile.kasan
  228. include scripts/Makefile.extrawarn
  230. # Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
  231. # last assignments
  232. KBUILD_CPPFLAGS += $(ARCH_CPPFLAGS) $(KCPPFLAGS)
  233. KBUILD_AFLAGS   += $(ARCH_AFLAGS)   $(KAFLAGS)
  234. KBUILD_CFLAGS   += $(ARCH_CFLAGS)   $(KCFLAGS)
  236. # Use --build-id when available.
  237. LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
  238.                   $(call cc-ldoption, -Wl$(comma)--build-id,))
  239. KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
  240. LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)
  242. ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
  243. LDFLAGS_vmlinux	+= $(call ld-option, -X,)
  244. endif
  246. # Default kernel image to build when no specific target is given.
  247. # KBUILD_IMAGE may be overruled on the command line or
  248. # set in the environment
  249. # Also any assignments in arch/$(ARCH)/Makefile take precedence over
  250. # this default value
  251. export KBUILD_IMAGE ?= vmlinux
  253. #
  254. # INSTALL_PATH specifies where to place the updated kernel and system map
  255. # images. Default is /boot, but you can set it to other values
  256. export  INSTALL_PATH ?= /boot
  258. #
  259. # INSTALL_DTBS_PATH specifies a prefix for relocations required by build roots.
  260. # Like INSTALL_MOD_PATH, it isn't defined in the Makefile, but can be passed as
  261. # an argument if needed. Otherwise it defaults to the kernel install path
  262. #
  263. export INSTALL_DTBS_PATH ?= $(INSTALL_PATH)/dtbs/$(KERNELRELEASE)
  265. #
  266. # INSTALL_MOD_PATH specifies a prefix to MODLIB for module directory
  267. # relocations required by build roots.  This is not defined in the
  268. # makefile but the argument can be passed to make if needed.
  269. #
  271. MODLIB  = $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
  272. export MODLIB
  274. #
  275. # INSTALL_MOD_STRIP, if defined, will cause modules to be
  276. # stripped after they are installed.  If INSTALL_MOD_STRIP is '1', then
  277. # the default option --strip-debug will be used.  Otherwise,
  278. # INSTALL_MOD_STRIP value will be used as the options to the strip command.
  280. ifdef INSTALL_MOD_STRIP
  281. ifeq ($(INSTALL_MOD_STRIP),1)
  282. mod_strip_cmd = $(STRIP) --strip-debug
  283. else
  284. mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
  285. endif # INSTALL_MOD_STRIP=1
  286. else
  287. mod_strip_cmd = true
  288. endif # INSTALL_MOD_STRIP
  289. export mod_strip_cmd
  291. # CONFIG_MODULE_COMPRESS, if defined, will cause module to be compressed
  292. # after they are installed in agreement with CONFIG_MODULE_COMPRESS_GZIP
  293. # or CONFIG_MODULE_COMPRESS_XZ.
  295. mod_compress_cmd = true
  296. ifdef CONFIG_MODULE_COMPRESS
  297.   ifdef CONFIG_MODULE_COMPRESS_GZIP
  298.     mod_compress_cmd = gzip -n -f
  299.   endif # CONFIG_MODULE_COMPRESS_GZIP
  300.   ifdef CONFIG_MODULE_COMPRESS_XZ
  301.     mod_compress_cmd = xz -f
  302.   endif # CONFIG_MODULE_COMPRESS_XZ
  303. endif # CONFIG_MODULE_COMPRESS
  304. export mod_compress_cmd
  306. # Select initial ramdisk compression format, default is gzip(1).
  307. # This shall be used by the dracut(8) tool while creating an initramfs image.
  308. #
  309. INITRD_COMPRESS-y                  := gzip
  310. INITRD_COMPRESS-$(CONFIG_RD_BZIP2) := bzip2
  311. INITRD_COMPRESS-$(CONFIG_RD_LZMA)  := lzma
  312. INITRD_COMPRESS-$(CONFIG_RD_XZ)    := xz
  313. INITRD_COMPRESS-$(CONFIG_RD_LZO)   := lzo
  314. INITRD_COMPRESS-$(CONFIG_RD_LZ4)   := lz4
  315. # do not export INITRD_COMPRESS, since we didn't actually
  316. # choose a sane default compression above.
  317. # export INITRD_COMPRESS := $(INITRD_COMPRESS-y)
  319. ifdef CONFIG_MODULE_SIG_ALL
  320. $(eval $(call config_filename,MODULE_SIG_KEY))
  322. mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY) certs/signing_key.x509
  323. else
  324. mod_sign_cmd = true
  325. endif
  326. export mod_sign_cmd
  329. ifeq ($(KBUILD_EXTMOD),)
  330. core-y      += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/
  332. # patsubst 函数表示字符串匹配替换
  333. vmlinux-dirs    := $(patsubst %/,%,$(filter %/, $(init-y) $(init-m) \
  334.              $(core-y) $(core-m) $(drivers-y) $(drivers-m) \
  335.              $(net-y) $(net-m) $(libs-y) $(libs-m) $(virt-y)))
  337. vmlinux-alldirs := $(sort $(vmlinux-dirs) $(patsubst %/,%,$(filter %/, \
  338.              $(init-) $(core-) $(drivers-) $(net-) $(libs-) $(virt-))))
  340. init-y      := $(patsubst %/, %/built-in.o, $(init-y))
  341. core-y      := $(patsubst %/, %/built-in.o, $(core-y))
  342. drivers-y   := $(patsubst %/, %/built-in.o, $(drivers-y))
  343. net-y       := $(patsubst %/, %/built-in.o, $(net-y))
  344. libs-y1     := $(patsubst %/, %/lib.a, $(libs-y))
  345. libs-y2     := $(patsubst %/, %/built-in.o, $(libs-y))
  346. libs-y      := $(libs-y1) $(libs-y2)
  347. virt-y      := $(patsubst %/, %/built-in.o, $(virt-y))
  349. # Externally visible symbols (used by link-vmlinux.sh)
  350. export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
  351. export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y) $(drivers-y) $(net-y) $(virt-y)
  352. export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
  353. export LDFLAGS_vmlinux
  354. # used by scripts/pacmage/Makefile
  355. export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)
  357. # 它是由内核代码下的每个顶级目录的built-in.o组成的。 
  358. vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)
  360. # Final link of vmlinux
  361.       cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
  362. quiet_cmd_link-vmlinux = LINK    $@
  364. # Include targets which we want to
  365. # execute if the rest of the kernel build went well.
  366. vmlinux: scripts/link-vmlinux.sh $(vmlinux-deps) FORCE
  367. ifdef CONFIG_HEADERS_CHECK
  368. 	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
  369. endif
  370. ifdef CONFIG_SAMPLES
  371.     $(Q)$(MAKE) $(build)=samples
  372. endif
  373. ifdef CONFIG_BUILD_DOCSRC
  374. 	$(Q)$(MAKE) $(build)=Documentation
  375. endif
  376. ifdef CONFIG_GDB_SCRIPTS
  377.     $(Q)ln -fsn `cd $(srctree) && /bin/pwd`/scripts/gdb/vmlinux-gdb.py
  378. endif
  379. 	+$(call if_changed,link-vmlinux)
  381. # The actual objects are generated when descending,
  382. # make sure no implicit rule kicks in
  383. # 可以看到 $(vmlinux-deps)这个目标依赖于$(vmlinux-dirs)这个目标
  384. $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
  386. # Handle descending into subdirectories listed in $(vmlinux-dirs)
  387. # Preset locale variables to speed up the build process. Limit locale
  388. # tweaks to this spot to avoid wrong language settings when running
  389. # make menuconfig etc.
  390. # Error messages still appears in the original language
  392. #  $(vmlinux-dirs)这个目标依赖于 prepare scripts这两个目标
  393. PHONY += $(vmlinux-dirs)
  394. $(vmlinux-dirs): prepare scripts
  395. 	$(Q)$(MAKE) $(build)=$@
  397. define filechk_kernel.release
  398.     echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
  399. endef
  401. # Store (new) KERNELRELEASE string in include/config/kernel.release
  402. include/config/kernel.release: include/config/auto.conf FORCE
  403.     $(call filechk,kernel.release)
  406. # Things we need to do before we recursively start building the kernel
  407. # or the modules are listed in "prepare".
  408. # A multi level approach is used. prepareN is processed before prepareN-1.
  409. # archprepare is used in arch Makefiles and when processed asm symlink,
  410. # version.h and scripts_basic is processed / created.

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