Kbuild.include 8.3 KB

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  1. ####
  2. # kbuild: Generic definitions
  3. # Convenient constants
  4. comma := ,
  5. squote := '
  6. empty :=
  7. space := $(empty) $(empty)
  8. ###
  9. # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
  10. dot-target = $(dir $@).$(notdir $@)
  11. ###
  12. # The temporary file to save gcc -MD generated dependencies must not
  13. # contain a comma
  14. depfile = $(subst $(comma),_,$(dot-target).d)
  15. ###
  16. # filename of target with directory and extension stripped
  17. basetarget = $(basename $(notdir $@))
  18. ###
  19. # Escape single quote for use in echo statements
  20. escsq = $(subst $(squote),'\$(squote)',$1)
  21. ###
  22. # filechk is used to check if the content of a generated file is updated.
  23. # Sample usage:
  24. # define filechk_sample
  25. # echo $KERNELRELEASE
  26. # endef
  27. # version.h : Makefile
  28. # $(call filechk,sample)
  29. # The rule defined shall write to stdout the content of the new file.
  30. # The existing file will be compared with the new one.
  31. # - If no file exist it is created
  32. # - If the content differ the new file is used
  33. # - If they are equal no change, and no timestamp update
  34. # - stdin is piped in from the first prerequisite ($<) so one has
  35. # to specify a valid file as first prerequisite (often the kbuild file)
  36. define filechk
  37. $(Q)set -e; \
  38. echo ' CHK $@'; \
  39. mkdir -p $(dir $@); \
  40. $(filechk_$(1)) < $< > $@.tmp; \
  41. if [ -r $@ ] && cmp -s $@ $@.tmp; then \
  42. rm -f $@.tmp; \
  43. else \
  44. echo ' UPD $@'; \
  45. mv -f $@.tmp $@; \
  46. fi
  47. endef
  48. ######
  49. # gcc support functions
  50. # See documentation in Documentation/kbuild/makefiles.txt
  51. # checker-shell
  52. # Usage: option = $(call checker-shell,$(CC)...-o $$OUT,option-ok,otherwise)
  53. # Exit code chooses option. $$OUT is safe location for needless output.
  54. define checker-shell
  55. $(shell set -e; \
  56. DIR=$(KBUILD_EXTMOD); \
  57. cd $${DIR:-$(objtree)}; \
  58. OUT=$$PWD/.$$$$.null; \
  59. \
  60. ln -s /dev/null $$OUT; \
  61. if $(1) >/dev/null 2>&1; \
  62. then echo "$(2)"; \
  63. else echo "$(3)"; \
  64. fi; \
  65. rm -f $$OUT)
  66. endef
  67. # as-option
  68. # Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
  69. as-option = $(call checker-shell,\
  70. $(CC) $(CFLAGS) $(1) -c -xassembler /dev/null -o $$OUT,$(1),$(2))
  71. # as-instr
  72. # Usage: cflags-y += $(call as-instr,instr,option1,option2)
  73. as-instr = $(call checker-shell,\
  74. printf "$(1)" | $(CC) $(AFLAGS) -c -xassembler -o $$OUT -,$(2),$(3))
  75. # cc-option
  76. # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
  77. cc-option = $(call checker-shell,\
  78. $(CC) $(CFLAGS) $(if $(3),$(3),$(1)) -S -xc /dev/null -o $$OUT,$(1),$(2))
  79. # cc-option-yn
  80. # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
  81. cc-option-yn = $(call cc-option,"y","n",$(1))
  82. # cc-option-align
  83. # Prefix align with either -falign or -malign
  84. cc-option-align = $(subst -functions=0,,\
  85. $(call cc-option,-falign-functions=0,-malign-functions=0))
  86. # cc-version
  87. # Usage gcc-ver := $(call cc-version,$(CC))
  88. cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
  89. # cc-ifversion
  90. # Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
  91. cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3))
  92. # ld-option
  93. # Usage: ldflags += $(call ld-option, -Wl$(comma)--hash-style=both)
  94. ld-option = $(call checker-shell,\
  95. $(CC) $(1) -nostdlib -xc /dev/null -o $$OUT,$(1),$(2))
  96. ######
  97. # Shorthand for $(Q)$(MAKE) -f scripts/Makefile.build obj=
  98. # Usage:
  99. # $(Q)$(MAKE) $(build)=dir
  100. build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
  101. # Prefix -I with $(srctree) if it is not an absolute path,
  102. # add original to the end
  103. addtree = $(if \
  104. $(filter-out -I/%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1))) $(1)
  105. # Find all -I options and call addtree
  106. flags = $(foreach o,$($(1)),\
  107. $(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o)))
  108. # echo command.
  109. # Short version is used, if $(quiet) equals `quiet_', otherwise full one.
  110. echo-cmd = $(if $($(quiet)cmd_$(1)),\
  111. echo ' $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
  112. # printing commands
  113. cmd = @$(echo-cmd) $(cmd_$(1))
  114. # Add $(obj)/ for paths that are not absolute
  115. objectify = $(foreach o,$(1),$(if $(filter /%,$(o)),$(o),$(obj)/$(o)))
  116. ###
  117. # if_changed - execute command if any prerequisite is newer than
  118. # target, or command line has changed
  119. # if_changed_dep - as if_changed, but uses fixdep to reveal dependencies
  120. # including used config symbols
  121. # if_changed_rule - as if_changed but execute rule instead
  122. # See Documentation/kbuild/makefiles.txt for more info
  123. ifneq ($(KBUILD_NOCMDDEP),1)
  124. # Check if both arguments has same arguments. Result is empty string, if equal.
  125. # User may override this check using make KBUILD_NOCMDDEP=1
  126. arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
  127. $(filter-out $(cmd_$@), $(cmd_$(1))) )
  128. endif
  129. # >'< substitution is for echo to work,
  130. # >$< substitution to preserve $ when reloading .cmd file
  131. # note: when using inline perl scripts [perl -e '...$$t=1;...']
  132. # in $(cmd_xxx) double $$ your perl vars
  133. make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))
  134. # Find any prerequisites that is newer than target or that does not exist.
  135. # PHONY targets skipped in both cases.
  136. any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
  137. # Execute command if command has changed or prerequisite(s) are updated.
  138. #
  139. if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
  140. @set -e; \
  141. $(echo-cmd) $(cmd_$(1)); \
  142. echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
  143. # Execute the command and also postprocess generated .d dependencies file.
  144. #
  145. if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \
  146. @set -e; \
  147. $(echo-cmd) $(cmd_$(1)); \
  148. scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
  149. rm -f $(depfile); \
  150. mv -f $(dot-target).tmp $(dot-target).cmd)
  151. # Will check if $(cmd_foo) changed, or any of the prerequisites changed,
  152. # and if so will execute $(rule_foo).
  153. # Usage: $(call if_changed_rule,foo)
  154. #
  155. if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ), \
  156. @set -e; \
  157. $(rule_$(1)))
  158. ###
  159. # why - tell why a a target got build
  160. # enabled by make V=2
  161. # Output (listed in the order they are checked):
  162. # (1) - due to target is PHONY
  163. # (2) - due to target missing
  164. # (3) - due to: file1.h file2.h
  165. # (4) - due to command line change
  166. # (5) - due to missing .cmd file
  167. # (6) - due to target not in $(targets)
  168. # (1) PHONY targets are always build
  169. # (2) No target, so we better build it
  170. # (3) Prerequisite is newer than target
  171. # (4) The command line stored in the file named dir/.target.cmd
  172. # differed from actual command line. This happens when compiler
  173. # options changes
  174. # (5) No dir/.target.cmd file (used to store command line)
  175. # (6) No dir/.target.cmd file and target not listed in $(targets)
  176. # This is a good hint that there is a bug in the kbuild file
  177. ifeq ($(KBUILD_VERBOSE),2)
  178. why = \
  179. $(if $(filter $@, $(PHONY)),- due to target is PHONY, \
  180. $(if $(wildcard $@), \
  181. $(if $(strip $(any-prereq)),- due to: $(any-prereq), \
  182. $(if $(arg-check), \
  183. $(if $(cmd_$@),- due to command line change, \
  184. $(if $(filter $@, $(targets)), \
  185. - due to missing .cmd file, \
  186. - due to $(notdir $@) not in $$(targets) \
  187. ) \
  188. ) \
  189. ) \
  190. ), \
  191. - due to target missing \
  192. ) \
  193. )
  194. echo-why = $(call escsq, $(strip $(why)))
  195. endif