1. 根目录:
2. Documentation
3. DocBook
4. Makefile

###
# This makefile is used to generate the kernel documentation,
# primarily based on in-line comments in various source files.
# See Documentation/kernel-doc-nano-HOWTO.txt for instruction in how
# to document the SRC - and how to read it.
# To add a new book the only step required is to add the book to the
# list of DOCBOOKS.

DOCBOOKS := z8530book.xml mcabook.xml device-drivers.xml \
	    kernel-hacking.xml kernel-locking.xml deviceiobook.xml \
	    writing_usb_driver.xml networking.xml \
	    kernel-api.xml filesystems.xml lsm.xml usb.xml kgdb.xml \
	    gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
	    genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
	    80211.xml debugobjects.xml sh.xml regulator.xml \
	    alsa-driver-api.xml writing-an-alsa-driver.xml \
	    tracepoint.xml media.xml drm.xml

###
# The build process is as follows (targets):
#              (xmldocs) [by docproc]
# file.tmpl --> file.xml +--> file.ps   (psdocs)   [by db2ps or xmlto]
#                        +--> file.pdf  (pdfdocs)  [by db2pdf or xmlto]
#                        +--> DIR=file  (htmldocs) [by xmlto]
#                        +--> man/      (mandocs)  [by xmlto]


# for PDF and PS output you can choose between xmlto and docbook-utils tools
PDF_METHOD	= $(prefer-db2x)
PS_METHOD	= $(prefer-db2x)


###
# The targets that may be used.
PHONY += xmldocs sgmldocs psdocs pdfdocs htmldocs mandocs installmandocs cleandocs xmldoclinks

BOOKS := $(addprefix $(obj)/,$(DOCBOOKS))
xmldocs: $(BOOKS)
sgmldocs: xmldocs

PS := $(patsubst %.xml, %.ps, $(BOOKS))
psdocs: $(PS)

PDF := $(patsubst %.xml, %.pdf, $(BOOKS))
pdfdocs: $(PDF)

HTML := $(sort $(patsubst %.xml, %.html, $(BOOKS)))
htmldocs: $(HTML) xmldoclinks
	$(call build_main_index)
	$(call build_images)

MAN := $(patsubst %.xml, %.9, $(BOOKS))
mandocs: $(MAN)

build_images = mkdir -p $(objtree)/Documentation/DocBook/media/ && \
	       cp $(srctree)/Documentation/DocBook/dvb/*.png \
	          $(srctree)/Documentation/DocBook/v4l/*.gif \
		  $(objtree)/Documentation/DocBook/media/

xmldoclinks:
ifneq ($(objtree),$(srctree))
	for dep in dvb media-entities.tmpl media-indices.tmpl v4l; do \
		rm -f $(objtree)/Documentation/DocBook/$$dep \
		&& ln -s $(srctree)/Documentation/DocBook/$$dep $(objtree)/Documentation/DocBook/ \
		|| exit; \
	done
endif

installmandocs: mandocs
	mkdir -p /usr/local/man/man9/
	install Documentation/DocBook/man/*.9.gz /usr/local/man/man9/

###
#External programs used
KERNELDOC = $(srctree)/scripts/kernel-doc
DOCPROC   = $(objtree)/scripts/basic/docproc

XMLTOFLAGS = -m $(srctree)/Documentation/DocBook/stylesheet.xsl
XMLTOFLAGS += --skip-validation

###
# DOCPROC is used for two purposes:
# 1) To generate a dependency list for a .tmpl file
# 2) To preprocess a .tmpl file and call kernel-doc with
#     appropriate parameters.
# The following rules are used to generate the .xml documentation
# required to generate the final targets. (ps, pdf, html).
quiet_cmd_docproc = DOCPROC $@
      cmd_docproc = SRCTREE=$(srctree)/ $(DOCPROC) doc $< >$@
define rule_docproc
	set -e;								\
        $(if $($(quiet)cmd_$(1)),echo '  $($(quiet)cmd_$(1))';) 	\
        $(cmd_$(1)); 							\
        ( 								\
          echo 'cmd_$@ := $(cmd_$(1))'; 				\
          echo $@: `SRCTREE=$(srctree) $(DOCPROC) depend $<`; 		\
        ) > $(dir $@).$(notdir $@).cmd
endef

%.xml: %.tmpl xmldoclinks FORCE
	$(call if_changed_rule,docproc)

###
#Read in all saved dependency files 
cmd_files := $(wildcard $(foreach f,$(BOOKS),$(dir $(f)).$(notdir $(f)).cmd))

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

###
# Changes in kernel-doc force a rebuild of all documentation
$(BOOKS): $(KERNELDOC)

# Tell kbuild to always build the programs
always := $(hostprogs-y)

notfoundtemplate = echo "*** You have to install docbook-utils or xmlto ***"; \
		   exit 1
db2xtemplate = db2TYPE -o $(dir $@) $<
xmltotemplate = xmlto TYPE $(XMLTOFLAGS) -o $(dir $@) $<

# determine which methods are available
ifeq ($(shell which db2ps >/dev/null 2>&1 && echo found),found)
	use-db2x = db2x
	prefer-db2x = db2x
else
	use-db2x = notfound
	prefer-db2x = $(use-xmlto)
endif
ifeq ($(shell which xmlto >/dev/null 2>&1 && echo found),found)
	use-xmlto = xmlto
	prefer-xmlto = xmlto
else
	use-xmlto = notfound
	prefer-xmlto = $(use-db2x)
endif

# the commands, generated from the chosen template
quiet_cmd_db2ps = PS      $@
      cmd_db2ps = $(subst TYPE,ps, $($(PS_METHOD)template))
%.ps : %.xml
	$(call cmd,db2ps)

quiet_cmd_db2pdf = PDF     $@
      cmd_db2pdf = $(subst TYPE,pdf, $($(PDF_METHOD)template))
%.pdf : %.xml
	$(call cmd,db2pdf)


index = index.html
main_idx = Documentation/DocBook/$(index)
build_main_index = rm -rf $(main_idx) && \
		   echo '<h1>Linux Kernel HTML Documentation</h1>' >> $(main_idx) && \
		   echo '<h2>Kernel Version: $(KERNELVERSION)</h2>' >> $(main_idx) && \
		   cat $(HTML) >> $(main_idx)

quiet_cmd_db2html = HTML    $@
      cmd_db2html = xmlto xhtml $(XMLTOFLAGS) -o $(patsubst %.html,%,$@) $< && \
		echo '<a HREF="$(patsubst %.html,%,$(notdir $@))/index.html"> \
        $(patsubst %.html,%,$(notdir $@))</a><p>' > $@

%.html:	%.xml
	@(which xmlto > /dev/null 2>&1) || \
	 (echo "*** You need to install xmlto ***"; \
	  exit 1)
	@rm -rf $@ $(patsubst %.html,%,$@)
	$(call cmd,db2html)
	@if [ ! -z "$(PNG-$(basename $(notdir $@)))" ]; then \
            cp $(PNG-$(basename $(notdir $@))) $(patsubst %.html,%,$@); fi

quiet_cmd_db2man = MAN     $@
      cmd_db2man = if grep -q refentry $<; then xmlto man $(XMLTOFLAGS) -o $(obj)/man $< ; gzip -f $(obj)/man/*.9; fi
%.9 : %.xml
	@(which xmlto > /dev/null 2>&1) || \
	 (echo "*** You need to install xmlto ***"; \
	  exit 1)
	$(Q)mkdir -p $(obj)/man
	$(call cmd,db2man)
	@touch $@

###
# Rules to generate postscripts and PNG images from .fig format files
quiet_cmd_fig2eps = FIG2EPS $@
      cmd_fig2eps = fig2dev -Leps $< $@

%.eps: %.fig
	@(which fig2dev > /dev/null 2>&1) || \
	 (echo "*** You need to install transfig ***"; \
	  exit 1)
	$(call cmd,fig2eps)

quiet_cmd_fig2png = FIG2PNG $@
      cmd_fig2png = fig2dev -Lpng $< $@

%.png: %.fig
	@(which fig2dev > /dev/null 2>&1) || \
	 (echo "*** You need to install transfig ***"; \
	  exit 1)
	$(call cmd,fig2png)

###
# Rule to convert a .c file to inline XML documentation
       gen_xml = :
 quiet_gen_xml = echo '  GEN     $@'
silent_gen_xml = :
%.xml: %.c
	@$($(quiet)gen_xml)
	@(                            \
	   echo "<programlisting>";   \
	   expand --tabs=8 < $< |     \
	   sed -e "s/&/\\&amp;/g"     \
	       -e "s/</\\&lt;/g"      \
	       -e "s/>/\\&gt;/g";     \
	   echo "</programlisting>")  > $@

###
# Help targets as used by the top-level makefile
dochelp:
	@echo  ' Linux kernel internal documentation in different formats:'
	@echo  '  htmldocs        - HTML'
	@echo  '  pdfdocs         - PDF'
	@echo  '  psdocs          - Postscript'
	@echo  '  xmldocs         - XML DocBook'
	@echo  '  mandocs         - man pages'
	@echo  '  installmandocs  - install man pages generated by mandocs'
	@echo  '  cleandocs       - clean all generated DocBook files'

###
# Temporary files left by various tools
clean-files := $(DOCBOOKS) \
	$(patsubst %.xml, %.dvi,  $(DOCBOOKS)) \
	$(patsubst %.xml, %.aux,  $(DOCBOOKS)) \
	$(patsubst %.xml, %.tex,  $(DOCBOOKS)) \
	$(patsubst %.xml, %.log,  $(DOCBOOKS)) \
	$(patsubst %.xml, %.out,  $(DOCBOOKS)) \
	$(patsubst %.xml, %.ps,   $(DOCBOOKS)) \
	$(patsubst %.xml, %.pdf,  $(DOCBOOKS)) \
	$(patsubst %.xml, %.html, $(DOCBOOKS)) \
	$(patsubst %.xml, %.9,    $(DOCBOOKS)) \
	$(index)

clean-dirs := $(patsubst %.xml,%,$(DOCBOOKS)) man

cleandocs:
	$(Q)rm -f $(call objectify, $(clean-files))
	$(Q)rm -rf $(call objectify, $(clean-dirs))

# Declare the contents of the .PHONY variable as phony.  We keep that
# information in a variable se we can use it in if_changed and friends.

.PHONY: $(PHONY)