# ==========================================================================
  # Installing headers
  #

  # header-y  - list files to be installed. They are preprocessed
  #             to remove __KERNEL__ section of the file

  # objhdr-y  - Same as header-y but for generated files

  # genhdr-y  - Same as objhdr-y but in a generated/ directory

  #
  # ==========================================================================

  # called may set destination dir (when installing to asm/)

  _dst := $(if $(dst),$(dst),$(obj))

  # generated header directory
  gen := $(if $(gen),$(gen),$(subst include/,include/generated/,$(obj)))

  kbuild-file := $(srctree)/$(obj)/Kbuild
  include $(kbuild-file)

  _dst := $(if $(destination-y),$(destination-y),$(_dst))

  include scripts/Kbuild.include

  install       := $(INSTALL_HDR_PATH)/$(_dst)

  header-y      := $(sort $(header-y))

  subdirs       := $(patsubst %/,%,$(filter %/, $(header-y)))
  header-y      := $(filter-out %/, $(header-y))

  # files used to track state of install/check
  install-file  := $(install)/.install
  check-file    := $(install)/.check

  # generic-y list all files an architecture uses from asm-generic
  # Use this to build a list of headers which require a wrapper
  wrapper-files := $(filter $(header-y), $(generic-y))

  # all headers files for this dir

  header-y      := $(filter-out $(generic-y), $(header-y))

  all-files     := $(header-y) $(objhdr-y) $(genhdr-y) $(wrapper-files)

  input-files   := $(addprefix $(srctree)/$(obj)/,$(header-y)) \

                   $(addprefix $(objtree)/$(obj)/,$(objhdr-y)) \
                   $(addprefix $(objtree)/$(gen)/,$(genhdr-y))

  output-files  := $(addprefix $(install)/, $(all-files))

  # Work out what needs to be removed
  oldheaders    := $(patsubst $(install)/%,%,$(wildcard $(install)/*.h))
  unwanted      := $(filter-out $(all-files),$(oldheaders))

  # Prefix unwanted with full paths to $(INSTALL_HDR_PATH)
  unwanted-file := $(addprefix $(install)/, $(unwanted))

  printdir = $(patsubst $(INSTALL_HDR_PATH)/%/,%,$(dir $@))

  quiet_cmd_install = INSTALL $(printdir) ($(words $(all-files))\
                              file$(if $(word 2, $(all-files)),s))

        cmd_install = \
          $(PERL) $< $(srctree)/$(obj) $(install) $(SRCARCH) $(header-y); \
          $(PERL) $< $(objtree)/$(obj) $(install) $(SRCARCH) $(objhdr-y); \

          $(PERL) $< $(objtree)/$(gen) $(install) $(SRCARCH) $(genhdr-y); \

          for F in $(wrapper-files); do                                   \
                  echo "\#include <asm-generic/$$F>" > $(install)/$$F;    \
          done;                                                           \

          touch $@

  quiet_cmd_remove = REMOVE  $(unwanted)
        cmd_remove = rm -f $(unwanted-file)

  quiet_cmd_check = CHECK   $(printdir) ($(words $(all-files)) files)

  # Headers list can be pretty long, xargs helps to avoid
  # the "Argument list too long" error.
        cmd_check = for f in $(all-files); do                          \
                    echo "$(install)/$${f}"; done                      \
                    | xargs                                            \
                    $(PERL) $< $(INSTALL_HDR_PATH)/include $(SRCARCH); \

  	          touch $@

  PHONY += __headersinst __headerscheck

  ifndef HDRCHECK
  # Rules for installing headers
  __headersinst: $(subdirs) $(install-file)
  	@:

  targets += $(install-file)
  $(install-file): scripts/headers_install.pl $(input-files) FORCE
  	$(if $(unwanted),$(call cmd,remove),)
  	$(if $(wildcard $(dir $@)),,$(shell mkdir -p $(dir $@)))
  	$(call if_changed,install)

  else

  __headerscheck: $(subdirs) $(check-file)
  	@:

  targets += $(check-file)
  $(check-file): scripts/headers_check.pl $(output-files) FORCE
  	$(call if_changed,check)

  endif

  # Recursion
  hdr-inst := -rR -f $(srctree)/scripts/Makefile.headersinst obj
  .PHONY: $(subdirs)
  $(subdirs):
  	$(Q)$(MAKE) $(hdr-inst)=$(obj)/$@ dst=$(_dst)/$@

  targets := $(wildcard $(sort $(targets)))
  cmd_files := $(wildcard \
               $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

  ifneq ($(cmd_files),)
  	include $(cmd_files)

  endif

  .PHONY: $(PHONY)
  PHONY += FORCE
  FORCE: ;