Kbuild

   1 #
   2 # Kbuild for top-level directory of the kernel
   3 # This file takes care of the following:
   4 # 1) Generate bounds.h
   5 # 2) Generate timeconst.h
   6 # 3) Generate asm-offsets.h (may need bounds.h and timeconst.h)
   7 # 4) Check for missing system calls
   8 # 5) Generate constants.py (may need bounds.h)
   9
  10 # Use filechk to avoid rebuilds when a header changes, but the resulting file
  11 # does not
  12 define filechk_offsets
  13         (set -e; \
  14          echo "#ifndef $2"; \
  15          echo "#define $2"; \
  16          echo "/*"; \
  17          echo " * DO NOT MODIFY."; \
  18          echo " *"; \
  19          echo " * This file was generated by Kbuild"; \
  20          echo " */"; \
  21          sed -ne '/#define/{s/\$$//;s/#//2;s/$$/*\//;p;}'; \
  22          echo "#endif" )
  23 endef
  24
  25 #####
  26 # 1) Generate bounds.h
  27
  28 bounds-file := include/generated/bounds.h
  29
  30 always  := $(bounds-file)
  31 targets := kernel/bounds.s
  32
  33 # We use internal kbuild rules to avoid the "is up to date" message from make
  34 kernel/bounds.s: kernel/bounds.c FORCE
  35         $(Q)mkdir -p $(dir $@)
  36         $(call if_changed_dep,cc_s_c)
  37
  38 $(obj)/$(bounds-file): kernel/bounds.s FORCE
  39         $(call filechk,offsets,__LINUX_BOUNDS_H__)
  40
  41 #####
  42 # 2) Generate timeconst.h
  43
  44 timeconst-file := include/generated/timeconst.h
  45
  46 targets += $(timeconst-file)
  47
  48 quiet_cmd_gentimeconst = GEN     $@
  49 define cmd_gentimeconst
  50         (echo $(CONFIG_HZ) | bc -q $< ) > $@
  51 endef
  52 define filechk_gentimeconst
  53         (echo $(CONFIG_HZ) | bc -q $< )
  54 endef
  55
  56 $(obj)/$(timeconst-file): kernel/time/timeconst.bc FORCE
  57         $(call filechk,gentimeconst)
  58
  59 #####
  60 # 3) Generate asm-offsets.h
  61 #
  62
  63 offsets-file := include/generated/asm-offsets.h
  64
  65 always  += $(offsets-file)
  66 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
  67
  68 # We use internal kbuild rules to avoid the "is up to date" message from make
  69 arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
  70                                       $(obj)/$(timeconst-file) $(obj)/$(bounds-file) FORCE
  71         $(Q)mkdir -p $(dir $@)
  72         $(call if_changed_dep,cc_s_c)
  73
  74 $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
  75         $(call filechk,offsets,__ASM_OFFSETS_H__)
  76
  77 #####
  78 # 4) Check for missing system calls
  79 #
  80
  81 always += missing-syscalls
  82 targets += missing-syscalls
  83
  84 quiet_cmd_syscalls = CALL    $<
  85       cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
  86
  87 missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
  88         $(call cmd,syscalls)
  89
  90 #####
  91 # 5) Generate constants for Python GDB integration
  92 #
  93
  94 extra-$(CONFIG_GDB_SCRIPTS) += build_constants_py
  95
  96 build_constants_py: $(obj)/$(timeconst-file) $(obj)/$(bounds-file)
  97         @$(MAKE) $(build)=scripts/gdb/linux $@
  98
  99 # Keep these three files during make clean
 100 no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)