OpenWrt KernelPackage分析
一. 前言
KernelPackage是OpenWrt用来编译内核模块的函数，其实KernelPackage后面会调用BuildPackage，这里会一块将BuildPackage也顺便分析，本文以gpio-button-hotplug驱动模块为例，讲解整个编译过程。
gpio-button-hotplug驱动编译命令如下：
make package/kernel/gpio-button-hotplug/compile V=s二. 编译过程分析
1. 编译命令运行分析
由前面的文章介绍了subdir的作用后，我们可以知道，subdir会将make package/kernel/gpio-button-hotplug/compile V=s命令转换为如下命令：
make -C package/kernel/gpio-button-hotplug compilemake会去到package/kernel/gpio-button-hotplug下找Makfile，并且找其中的compile目标运行，gpio-button-hotplug的Makefile如下：
include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/kernel.mk
PKG_NAME:=gpio-button-hotplug
PKG_RELEASE:=3
PKG_LICENSE:=GPL-2.0
include $(INCLUDE_DIR)/package.mk
define KernelPackage/gpio-button-hotplug
......
endef
......
MAKE_OPTS:= $(KERNEL_MAKE_FLAGS) M="$(PKG_BUILD_DIR)"
define Build/Compile
$(MAKE) -C "$(LINUX_DIR)" $(MAKE_OPTS) modules
endef
$(eval $(call KernelPackage,gpio-button-hotplug))可以看到，这里会调用到KernelPackage，KernelPackage内容如下：
include/kernel.mk:
define KernelPackage
NAME:=$(1)
$(eval $(call Package/Default))
$(eval $(call KernelPackage/Defaults))
$(eval $(call KernelPackage/$(1)))
$(eval $(call KernelPackage/$(1)/$(BOARD)))
$(eval $(call KernelPackage/$(1)/$(BOARD)/$(if $(SUBTARGET),$(SUBTARGET),generic)))
define Package/kmod-$(1)
TITLE:=$(TITLE)
SECTION:=kernel
CATEGORY:=Kernel modules
DESCRIPTION:=$(DESCRIPTION)
EXTRA_DEPENDS:=kernel (=$(LINUX_VERSION)-$(LINUX_RELEASE)-$(LINUX_VERMAGIC))
VERSION:=$(LINUX_VERSION)$(if $(PKG_VERSION),+$(PKG_VERSION))-$(if $(PKG_RELEASE),$(PKG_RELEASE),$(LINUX_RELEASE))
PKGFLAGS:=$(PKGFLAGS)
$(call KernelPackage/$(1))
$(call KernelPackage/$(1)/$(BOARD))
$(call KernelPackage/$(1)/$(BOARD)/$(if $(SUBTARGET),$(SUBTARGET),generic))
endef
ifdef KernelPackage/$(1)/conffiles
define Package/kmod-$(1)/conffiles
$(call KernelPackage/$(1)/conffiles)
endef
endif
ifdef KernelPackage/$(1)/description
define Package/kmod-$(1)/description
$(call KernelPackage/$(1)/description)
endef
endif
ifdef KernelPackage/$(1)/config
define Package/kmod-$(1)/config
$(call KernelPackage/$(1)/config)
endef
endif
$(call KernelPackage/depends)
$(call KernelPackage/hooks)
ifneq ($(if $(filter-out %=y %=n %=m,$(KCONFIG)),$(filter m y,$(foreach c,$(filter-out %=y %=n %=m,$(KCONFIG)),$($(c)))),.),)
define Package/kmod-$(1)/install
@for mod in $$(call version_filter,$$(FILES)); do \
if grep -q "$$$$$$$${mod##$(LINUX_DIR)/}" "$(LINUX_DIR)/modules.builtin"; then \
echo "<<2>>" \
echo "NOTICE: module '$$$$$$$$mod' is built-in."; \
elif [ -e $$$$$$$$mod ]; then \
echo "<<3>> $$$$$$$$mod" ; \
mkdir -p $$(1)/$(MODULES_SUBDIR) ; \
$(CP) -L $$$$$$$$mod $$(1)/$(MODULES_SUBDIR)/ ; \
else \
echo "ERROR: module '$$$$$$$$mod' is missing." >&2; \
exit 1; \
fi; \
done;
$(call ModuleAutoLoad,$(1),$$(1),$(filter-out 0-,$(word 1,$(AUTOLOAD))-),$(filter-out 0,$(word 2,$(AUTOLOAD))),$(sort $(wordlist 3,99,$(AUTOLOAD))))
$(call KernelPackage/$(1)/install,$$(1))
endef
$(if $(CONFIG_PACKAGE_kmod-$(1)),
else
compile: $(1)-disabled
$(1)-disabled:
@echo "WARNING: kmod-$(1) is not available in the kernel config - generating empty package" >&2
define Package/kmod-$(1)/install
echo "<<1>>"
true
endef
)
endif
$$(eval $$(call BuildPackage,kmod-$(1)))
$$(IPKG_kmod-$(1)): $$(wildcard $$(call version_filter,$$(FILES)))
endef细节先不分析，先找compile目标，可以看到KernelPackage下没有compile目标，原因如下：
ifneq ($(if $(filter-out %=y %=n %=m,$(KCONFIG)),$(filter m y,$(foreach c,$(filter-out %=y %=n %=m,$(KCONFIG)),$($(c)))),.),)
如上代码KCONFIG变量（package/kernel/linux/modules/*.mk才有定义）为空，所以以上表达式可以写为ifneq (.,)，结果为真，执行上面的分支，上面分支没有compile目标。
此时，就要到BuildPackage里面寻找了。BuildPackage代码如下：
define BuildPackage
$(eval $(Package/Default))
$(eval $(Package/$(1)))
ifdef DESCRIPTION
$$(error DESCRIPTION:= is obsolete, use Package/PKG_NAME/description)
endif
ifndef Package/$(1)/description
define Package/$(1)/description
$(TITLE)
endef
endif
BUILD_PACKAGES += $(1)
$(STAMP_PREPARED): $$(if $(QUILT)$(DUMP),,$(call find_library_dependencies,$(1)))
$(foreach FIELD, TITLE CATEGORY SECTION VERSION,
ifeq ($($(FIELD)),)
$$(error Package/$(1) is missing the $(FIELD) field)
endif
)
$(if $(DUMP), \
$(if $(CHECK),,$(Dumpinfo/Package)), \
$(foreach target, \
$(if $(Package/$(1)/targets),$(Package/$(1)/targets), \
$(if $(PKG_TARGETS),$(PKG_TARGETS), ipkg) \
), $(BuildTarget/$(target)) \
) \
)
$(if $(PKG_HOST_ONLY),,$(call Build/DefaultTargets,$(1)))
endef这里也没有compile目标。我们分析里面如下代码：
$(if $(DUMP), \
$(if $(CHECK),,$(Dumpinfo/Package)), \
$(foreach target, \
$(if $(Package/$(1)/targets),$(Package/$(1)/targets), \
$(if $(PKG_TARGETS),$(PKG_TARGETS), ipkg) \
), $(BuildTarget/$(target)) \
) \
)
以上代码不难分析，结果为$(BuildTarget/ipkg)。接下来分析BuildTarget/ipkg，代码如下：
define BuildTarget/ipkg
ABIV_$(1):=$(call FormatABISuffix,$(1),$(ABI_VERSION))
PDIR_$(1):=$(call FeedPackageDir,$(1))
IPKG_$(1):=$$(PDIR_$(1))/$(1)$$(ABIV_$(1))_$(VERSION)_$(PKGARCH).ipk
IDIR_$(1):=$(PKG_BUILD_DIR)/ipkg-$(PKGARCH)/$(1)
KEEP_$(1):=$(strip $(call Package/$(1)/conffiles))
ifeq ($(BUILD_VARIANT),$$(if $$(VARIANT),$$(VARIANT),$(BUILD_VARIANT)))
do_install=
ifdef Package/$(1)/install
do_install=yes
endif
ifdef Package/$(1)/install-overlay
do_install=yes
endif
ifdef do_install
ifneq ($(CONFIG_PACKAGE_$(1))$(DEVELOPER),)
IPKGS += $(1)
$(_pkg_target)compile: $$(IPKG_$(1)) $(PKG_INFO_DIR)/$(1).provides $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
prepare-package-install: $$(IPKG_$(1))
compile: $(STAGING_DIR_ROOT)/stamp/.$(1)_installed
else
$(if $(CONFIG_PACKAGE_$(1)),$$(info WARNING: skipping $(1) -- package not selected))
endif
.PHONY: $(PKG_INSTALL_STAMP).$(1)
ifeq ($(CONFIG_PACKAGE_$(1)),y)
compile: $(PKG_INSTALL_STAMP).$(1)
endif
$(PKG_INSTALL_STAMP).$(1): prepare-package-install
echo "$(1)" >> $(PKG_INSTALL_STAMP)
else
$(if $(CONFIG_PACKAGE_$(1)),$$(warning WARNING: skipping $(1) -- package has no install section))
endif
endif
DEPENDS:=$(call PKG_FIXUP_DEPENDS,$(1),$(DEPENDS))
IDEPEND_$(1):=$$(call filter_deps,$$(DEPENDS))
IDEPEND += $$(patsubst %,$(1):%,$$(IDEPEND_$(1)))
$(FixupDependencies)
$(FixupReverseDependencies)
$(eval $(call BuildIPKGVariable,$(1),conffiles))
$(eval $(call BuildIPKGVariable,$(1),preinst,,1))
$(eval $(call BuildIPKGVariable,$(1),postinst,-pkg,1))
$(eval $(call BuildIPKGVariable,$(1),prerm,-pkg,1))
$(eval $(call BuildIPKGVariable,$(1),postrm,,1))
$(PKG_BUILD_DIR)/.pkgdir/$(1).installed : export PATH=$$(TARGET_PATH_PKG)
$(PKG_BUILD_DIR)/.pkgdir/$(1).installed: $(STAMP_BUILT)
rm -rf $$@ $(PKG_BUILD_DIR)/.pkgdir/$(1)
mkdir -p $(PKG_BUILD_DIR)/.pkgdir/$(1)
$(call Package/$(1)/install,$(PKG_BUILD_DIR)/.pkgdir/$(1))
$(call Package/$(1)/install_lib,$(PKG_BUILD_DIR)/.pkgdir/$(1))
touch $$@
$(STAGING_DIR_ROOT)/stamp/.$(1)_installed: $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
mkdir -p $(STAGING_DIR_ROOT)/stamp
$(if $(ABI_VERSION),echo '$(ABI_VERSION)' | cmp -s - $(PKG_INFO_DIR)/$(1).version || { \
echo '$(ABI_VERSION)' > $(PKG_INFO_DIR)/$(1).version; \
$(foreach pkg,$(filter-out $(1),$(PROVIDES)), \
cp $(PKG_INFO_DIR)/$(1).version $(PKG_INFO_DIR)/$(pkg).version; \
) \
} )
$(call locked,$(CP) $(PKG_BUILD_DIR)/.pkgdir/$(1)/. $(STAGING_DIR_ROOT)/,root-copy)
touch $$@
Package/$(1)/DEPENDS := $$(call mergelist,$$(foreach dep,$$(filter-out @%,$$(IDEPEND_$(1))),$$(dep)$$(call GetABISuffix,$$(dep))))
ifneq ($$(EXTRA_DEPENDS),)
Package/$(1)/DEPENDS := $$(EXTRA_DEPENDS)$$(if $$(Package/$(1)/DEPENDS),$$(comma) $$(Package/$(1)/DEPENDS))
endif
$(_define) Package/$(1)/CONTROL
Package: $(1)$$(ABIV_$(1))
Version: $(VERSION)
$$(call addfield,Depends,$$(Package/$(1)/DEPENDS)
)$$(call addfield,Conflicts,$$(call mergelist,$(CONFLICTS))
)$$(call addfield,Provides,$$(call mergelist,$$(filter-out $(1)$$(ABIV_$(1)),$(PROVIDES)$$(if $$(ABIV_$(1)), $(1) $(foreach provide,$(PROVIDES),$(provide)$$(ABIV_$(1))))))
)$$(call addfield,Alternatives,$$(call mergelist,$(ALTERNATIVES))
)$$(call addfield,Source,$(SOURCE)
)$$(call addfield,SourceName,$(1)
)$$(call addfield,License,$(LICENSE)
)$$(call addfield,LicenseFiles,$(LICENSE_FILES)
)$$(call addfield,Section,$(SECTION)
)$$(call addfield,Require-User,$(USERID)
)$$(call addfield,SourceDateEpoch,$(PKG_SOURCE_DATE_EPOCH)
)$$(if $$(ABIV_$(1)),ABIVersion: $$(ABIV_$(1))
)$(if $(PKG_CPE_ID),CPE-ID: $(PKG_CPE_ID)
)$(if $(filter hold,$(PKG_FLAGS)),Status: unknown hold not-installed
)$(if $(filter essential,$(PKG_FLAGS)),Essential: yes
)$(if $(MAINTAINER),Maintainer: $(MAINTAINER)
)Architecture: $(PKGARCH)
Installed-Size: 0
$(_endef)
$$(IPKG_$(1)) : export CONTROL=$$(Package/$(1)/CONTROL)
$$(IPKG_$(1)) : export DESCRIPTION=$$(Package/$(1)/description)
$$(IPKG_$(1)) : export PATH=$$(TARGET_PATH_PKG)
$$(IPKG_$(1)) : export PKG_SOURCE_DATE_EPOCH:=$(PKG_SOURCE_DATE_EPOCH)
$(PKG_INFO_DIR)/$(1).provides $$(IPKG_$(1)): $(STAMP_BUILT) $(INCLUDE_DIR)/package-ipkg.mk
@rm -rf $$(IDIR_$(1)); \
$$(call remove_ipkg_files,$(1),$$(call opkg_package_files,$(call gen_ipkg_wildcard,$(1))))
mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/CONTROL $(PKG_INFO_DIR)
$(call Package/$(1)/install,$$(IDIR_$(1)))
$(if $(Package/$(1)/install-overlay),mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/rootfs-overlay)
$(call Package/$(1)/install-overlay,$$(IDIR_$(1))/rootfs-overlay)
-find $$(IDIR_$(1)) -name 'CVS' -o -name '.svn' -o -name '.#*' -o -name '*~'| $(XARGS) rm -rf
@( \
find $$(IDIR_$(1)) -name lib\*.so\* -or -name \*.ko | awk -F/ '{ print $$$$NF }'; \
for file in $$(patsubst %,$(PKG_INFO_DIR)/%.provides,$$(IDEPEND_$(1))); do \
if [ -f "$$$$file" ]; then \
cat $$$$file; \
fi; \
done; $(Package/$(1)/extra_provides) \
) | sort -u > $(PKG_INFO_DIR)/$(1).provides
$(if $(PROVIDES),@for pkg in $(filter-out $(1),$(PROVIDES)); do cp $(PKG_INFO_DIR)/$(1).provides $(PKG_INFO_DIR)/$$$$pkg.provides; done)
$(CheckDependencies)
$(RSTRIP) $$(IDIR_$(1))
ifneq ($$(CONFIG_IPK_FILES_CHECKSUMS),)
(cd $$(IDIR_$(1)); \
( \
find . -type f \! -path ./CONTROL/\* -exec mkhash sha256 -n \{\} \; 2> /dev/null | \
sed 's|\([[:blank:]]\)\./| \1/|' > $$(IDIR_$(1))/CONTROL/files-sha256sum \
) || true \
)
endif
(cd $$(IDIR_$(1))/CONTROL; \
( \
echo "$$$$CONTROL"; \
printf "Description: "; echo "$$$$DESCRIPTION" | sed -e 's,^[[:space:]]*, ,g'; \
) > control; \
chmod 644 control; \
( \
echo "#!/bin/sh"; \
echo "[ \"\$$$${IPKG_NO_SCRIPT}\" = \"1\" ] && exit 0"; \
echo "[ -s "\$$$${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; \
echo ". \$$$${IPKG_INSTROOT}/lib/functions.sh"; \
echo "default_postinst \$$$$0 \$$$$@"; \
) > postinst; \
( \
echo "#!/bin/sh"; \
echo "[ -s "\$$$${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; \
echo ". \$$$${IPKG_INSTROOT}/lib/functions.sh"; \
echo "default_prerm \$$$$0 \$$$$@"; \
) > prerm; \
chmod 0755 postinst prerm; \
$($(1)_COMMANDS) \
)
ifneq ($$(KEEP_$(1)),)
@( \
keepfiles=""; \
for x in $$(KEEP_$(1)); do \
[ -f "$$(IDIR_$(1))/$$$$x" ] || keepfiles="$$$${keepfiles:+$$$$keepfiles }$$$$x"; \
done; \
[ -z "$$$$keepfiles" ] || { \
mkdir -p $$(IDIR_$(1))/lib/upgrade/keep.d; \
for x in $$$$keepfiles; do echo $$$$x >> $$(IDIR_$(1))/lib/upgrade/keep.d/$(1); done; \
}; \
)
endif
$(INSTALL_DIR) $$(PDIR_$(1))
$(FAKEROOT) $(SCRIPT_DIR)/ipkg-build -m "$(FILE_MODES)" $$(IDIR_$(1)) $$(PDIR_$(1))
@[ -f $$(IPKG_$(1)) ]
$(1)-clean:
$$(call remove_ipkg_files,$(1),$$(call opkg_package_files,$(call gen_ipkg_wildcard,$(1))))
clean: $(1)-clean
endef里面一段一段分析，如下：
ifeq ($(BUILD_VARIANT),$$(if $$(VARIANT),$$(VARIANT),$(BUILD_VARIANT)))
do_install=
ifdef Package/$(1)/install
do_install=yes
endif
ifdef Package/$(1)/install-overlay
do_install=yes
endif
ifdef do_install
ifneq ($(CONFIG_PACKAGE_$(1))$(DEVELOPER),)
IPKGS += $(1)
$(_pkg_target)compile: $$(IPKG_$(1)) $(PKG_INFO_DIR)/$(1).provides $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
prepare-package-install: $$(IPKG_$(1))
compile: $(STAGING_DIR_ROOT)/stamp/.$(1)_installed
else
$(if $(CONFIG_PACKAGE_$(1)),$$(info WARNING: skipping $(1) -- package not selected))
endif.PHONY: $(PKG_INSTALL_STAMP).$(1)
ifeq ($(CONFIG_PACKAGE_$(1)),y)
compile: $(PKG_INSTALL_STAMP).$(1)
endif
$(PKG_INSTALL_STAMP).$(1): prepare-package-install
echo "$(1)" >> $(PKG_INSTALL_STAMP)
else
$(if $(CONFIG_PACKAGE_$(1)),$$(warning WARNING: skipping $(1) -- package has no install section))
endif
endif
由于BUILD_VARIANT和VARIANT都未定义，都为空，自然相等，所以条件成立。
由于Package/$(1)/install定义在include/kernel.mk中，如下：
include/kernel.mk:
define Package/kmod-$(1)/install
@for mod in $$(call version_filter,$$(FILES)); do \
if grep -q "$$$$$$$${mod##$(LINUX_DIR)/}" "$(LINUX_DIR)/modules.builtin"; then \
echo "NOTICE: module '$$$$$$$$mod' is built-in."; \
elif [ -e $$$$$$$$mod ]; then \
mkdir -p $$(1)/$(MODULES_SUBDIR) ; \
$(CP) -L $$$$$$$$mod $$(1)/$(MODULES_SUBDIR)/ ; \
else \
echo "ERROR: module '$$$$$$$$mod' is missing." >&2; \
exit 1; \
fi; \
done;
$(call ModuleAutoLoad,$(1),$$(1),$(filter-out 0-,$(word 1,$(AUTOLOAD))-),$(filter-out 0,$(word 2,$(AUTOLOAD))),$(sort $(wordlist 3,99,$(AUTOLOAD))))
$(call KernelPackage/$(1)/install,$$(1))
endef所以do_install变量的值是yes。以上的结果可以通过$(warning $(Package/$(1)/install))打印出来证实。
由于，do_install=yes，此时，可以找到compile目标了，这里有两个compile目标，两个compile目标会依次运行，compile目标和为什么这么运行的例子如下：
include/package-ipkg.mk:
compile: $(STAGING_DIR_ROOT)/stamp/.$(1)_installed
......
compile: $(PKG_INSTALL_STAMP).$(1)
example：
act1:
@echo act1;
act2:
@echo act2;
compile: act1
compile: act2
all: compile
@echo all
result：
act1
act2
all2. 先来分析第一个compile目标
$(STAGING_DIR_ROOT)/stamp/.$(1)_installed依赖于$(PKG_BUILD_DIR)/.pkgdir/$(1).installed，实现如下：
include/package-ipkg.mk:
$(STAGING_DIR_ROOT)/stamp/.$(1)_installed: $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
mkdir -p $(STAGING_DIR_ROOT)/stamp
$(if $(ABI_VERSION),echo '$(ABI_VERSION)' | cmp -s - $(PKG_INFO_DIR)/$(1).version || { \
echo '$(ABI_VERSION)' > $(PKG_INFO_DIR)/$(1).version; \
$(foreach pkg,$(filter-out $(1),$(PROVIDES)), \
cp $(PKG_INFO_DIR)/$(1).version $(PKG_INFO_DIR)/$(pkg).version; \
) \
} )
$(call locked,$(CP) $(PKG_BUILD_DIR)/.pkgdir/$(1)/. $(STAGING_DIR_ROOT)/,root-copy)
touch $$@$(PKG_BUILD_DIR)/.pkgdir/$(1).installed依赖于STAMP_BUILT，实现如下：
include/package-ipkg.mk:
$(PKG_BUILD_DIR)/.pkgdir/$(1).installed: $(STAMP_BUILT)
rm -rf $$@ $(PKG_BUILD_DIR)/.pkgdir/$(1)
mkdir -p $(PKG_BUILD_DIR)/.pkgdir/$(1)
$(call Package/$(1)/install,$(PKG_BUILD_DIR)/.pkgdir/$(1))
$(call Package/$(1)/install_lib,$(PKG_BUILD_DIR)/.pkgdir/$(1))
touch $$@STAMP_BUILT定义在Build/CoreTargets，Build/CoreTargets实现如下：
include/package.mk:
define Build/CoreTargets
STAMP_PREPARED:=$$(STAMP_PREPARED)
STAMP_CONFIGURED:=$$(STAMP_CONFIGURED)
$(if $(QUILT),$(Build/Quilt))
$(call Build/Autoclean)
$(call DefaultTargets)
$(DL_DIR)/$(FILE): FORCE
download:
$(foreach hook,$(Hooks/Download),
$(call $(hook))$(sep)
)
$(STAMP_PREPARED) : export PATH=$$(TARGET_PATH_PKG)
$(STAMP_PREPARED): $(STAMP_PREPARED_DEPENDS)
@-rm -rf $(PKG_BUILD_DIR)
@mkdir -p $(PKG_BUILD_DIR)
touch $$@_check
$(foreach hook,$(Hooks/Prepare/Pre),$(call $(hook))$(sep))
$(Build/Prepare)
$(foreach hook,$(Hooks/Prepare/Post),$(call $(hook))$(sep))
touch $$@
$(call Build/Exports,$(STAMP_CONFIGURED))
$(STAMP_CONFIGURED): $(STAMP_PREPARED) $(STAMP_CONFIGURED_DEPENDS)
rm -f $(STAMP_CONFIGURED_WILDCARD)
$(CleanStaging)
$(foreach hook,$(Hooks/Configure/Pre),$(call $(hook))$(sep))
$(Build/Configure)
$(foreach hook,$(Hooks/Configure/Post),$(call $(hook))$(sep))
touch $$@
$(call Build/Exports,$(STAMP_BUILT))
$(STAMP_BUILT): $(STAMP_CONFIGURED) $(STAMP_BUILT_DEPENDS)
rm -f $$@
touch $$@_check
$(foreach hook,$(Hooks/Compile/Pre),$(call $(hook))$(sep))
$(Build/Compile)
$(foreach hook,$(Hooks/Compile/Post),$(call $(hook))$(sep))
$(Build/Install)
$(foreach hook,$(Hooks/Install/Post),$(call $(hook))$(sep))
touch $$@
$(STAMP_INSTALLED) : export PATH=$$(TARGET_PATH_PKG)
$(STAMP_INSTALLED): $(STAMP_BUILT)
rm -rf $(TMP_DIR)/stage-$(PKG_DIR_NAME)
mkdir -p $(TMP_DIR)/stage-$(PKG_DIR_NAME)/host $(STAGING_DIR)/packages
$(foreach hook,$(Hooks/InstallDev/Pre),\
$(call $(hook),$(TMP_DIR)/stage-$(PKG_DIR_NAME),$(TMP_DIR)/stage-$(PKG_DIR_NAME)/host)$(sep)\
)
$(call Build/InstallDev,$(TMP_DIR)/stage-$(PKG_DIR_NAME),$(TMP_DIR)/stage-$(PKG_DIR_NAME)/host)
$(foreach hook,$(Hooks/InstallDev/Post),\
$(call $(hook),$(TMP_DIR)/stage-$(PKG_DIR_NAME),$(TMP_DIR)/stage-$(PKG_DIR_NAME)/host)$(sep)\
)
if [ -f $(STAGING_DIR)/packages/$(STAGING_FILES_LIST) ]; then \
$(SCRIPT_DIR)/clean-package.sh \
"$(STAGING_DIR)/packages/$(STAGING_FILES_LIST)" \
"$(STAGING_DIR)"; \
fi
if [ -d $(TMP_DIR)/stage-$(PKG_DIR_NAME) ]; then \
(cd $(TMP_DIR)/stage-$(PKG_DIR_NAME); find ./ > $(TMP_DIR)/stage-$(PKG_DIR_NAME).files); \
$(call locked, \
mv $(TMP_DIR)/stage-$(PKG_DIR_NAME).files $(STAGING_DIR)/packages/$(STAGING_FILES_LIST) && \
$(CP) $(TMP_DIR)/stage-$(PKG_DIR_NAME)/* $(STAGING_DIR)/; \
,staging-dir); \
fi
rm -rf $(TMP_DIR)/stage-$(PKG_DIR_NAME)
touch $$@
ifdef Build/InstallDev
$(_pkg_target)compile: $(STAMP_INSTALLED)
endif
$(_pkg_target)prepare: $(STAMP_PREPARED)
$(_pkg_target)configure: $(STAMP_CONFIGURED)
$(_pkg_target)dist: $(STAMP_CONFIGURED)
$(_pkg_target)distcheck: $(STAMP_CONFIGURED)
ifneq ($(CONFIG_AUTOREMOVE),)
compile:
-touch -r $(PKG_BUILD_DIR)/.built $(PKG_BUILD_DIR)/.autoremove 2>/dev/null >/dev/null
$(FIND) $(PKG_BUILD_DIR) -mindepth 1 -maxdepth 1 -not '(' -type f -and -name '.*' -and -size 0 ')' -and -not -name '.pkgdir' | \
$(XARGS) rm -rf
endif
endef
define Build/DefaultTargets
$(if $(USE_SOURCE_DIR)$(USE_GIT_TREE)$(USE_GIT_SRC_CHECKOUT),,$(if $(strip $(PKG_SOURCE_URL)),$(call Download,default)))
$(if $(DUMP),,$(Build/CoreTargets))
define Build/DefaultTargets
endef
endef
define BuildPackage
......
$(if $(PKG_HOST_ONLY),,$(call Build/DefaultTargets,$(1)))
endef其中
$(STAMP_BUILT): $(STAMP_CONFIGURED) $(STAMP_BUILT_DEPENDS)
rm -f $$@
touch $$@_check
$(foreach hook,$(Hooks/Compile/Pre),$(call $(hook))$(sep))
$(Build/Compile)
$(foreach hook,$(Hooks/Compile/Post),$(call $(hook))$(sep))
$(Build/Install)
$(foreach hook,$(Hooks/Install/Post),$(call $(hook))$(sep))
touch $$@
STAMP_BUILT依赖于STAMP_CONFIGURED和STAMP_BUILT_DEPENDS，STAMP_CONFIGURED实现如下：
$(STAMP_CONFIGURED): $(STAMP_PREPARED) $(STAMP_CONFIGURED_DEPENDS)
rm -f $(STAMP_CONFIGURED_WILDCARD)
$(CleanStaging)
$(foreach hook,$(Hooks/Configure/Pre),$(call $(hook))$(sep))
$(Build/Configure)
$(foreach hook,$(Hooks/Configure/Post),$(call $(hook))$(sep))
touch $$@
STAMP_CONFIGURED依赖于STAMP_PREPARED，STAMP_PREPARED实现如下：
(STAMP_PREPARED) : export PATH=$$(TARGET_PATH_PKG)
$(STAMP_PREPARED): $(STAMP_PREPARED_DEPENDS)
@-rm -rf $(PKG_BUILD_DIR)
@mkdir -p $(PKG_BUILD_DIR)
touch $$@_check
$(foreach hook,$(Hooks/Prepare/Pre),$(call $(hook))$(sep))
$(Build/Prepare)
$(foreach hook,$(Hooks/Prepare/Post),$(call $(hook))$(sep))
touch $$@
经过这几个步骤，kmod-*.ipkg的代码就编译好了。步骤分别是BUild/Prepare，CleanStaging，Build/Configure，Build/Compile和Build/Install。
在之后，执行如下代码
include/package-ipkg.mk:
$(PKG_BUILD_DIR)/.pkgdir/$(1).installed : export PATH=$$(TARGET_PATH_PKG)
$(PKG_BUILD_DIR)/.pkgdir/$(1).installed: $(STAMP_BUILT)
rm -rf $$@ $(PKG_BUILD_DIR)/.pkgdir/$(1)
mkdir -p $(PKG_BUILD_DIR)/.pkgdir/$(1)
$(call Package/$(1)/install,$(PKG_BUILD_DIR)/.pkgdir/$(1))
$(call Package/$(1)/install_lib,$(PKG_BUILD_DIR)/.pkgdir/$(1))
touch $$@实际运行代码：
rm -rf /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug.installed /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug
mkdir -p /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug
mkdir -p /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug/etc/modules.d; ( echo "gpio-button-hotplug"; ) > /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug/etc/modules.d/30-gpio-button-hotplug; mkdir -p /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug/etc/modules-boot.d; ln -sf ../modules.d/30-gpio-button-hotplug /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug/etc/modules-boot.d/;
touch /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug.installed创建build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug.installed文件。
$(STAGING_DIR_ROOT)/stamp/.$(1)_installed: $(PKG_BUILD_DIR)/.pkgdir/$(1).installed
mkdir -p $(STAGING_DIR_ROOT)/stamp
$(if $(ABI_VERSION),echo '$(ABI_VERSION)' | cmp -s - $(PKG_INFO_DIR)/$(1).version || { \
echo '$(ABI_VERSION)' > $(PKG_INFO_DIR)/$(1).version; \
$(foreach pkg,$(filter-out $(1),$(PROVIDES)), \
cp $(PKG_INFO_DIR)/$(1).version $(PKG_INFO_DIR)/$(pkg).version; \
) \
} )
$(call locked,$(CP) $(PKG_BUILD_DIR)/.pkgdir/$(1)/. $(STAGING_DIR_ROOT)/,root-copy)
touch $$@执行如下：
mkdir -p /root/mt7981/openwrt/staging_dir/target-aarch64_cortex-a53_musl/root-mediatek/stamp
SHELL= flock /root/mt7981/openwrt/tmp/.root-copy.flock -c 'cp -fpR /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/.pkgdir/kmod-gpio-button-hotplug/. /root/mt7981/openwrt/staging_dir/target-aarch64_cortex-a53_musl/root-mediatek/'
touch /root/mt7981/openwrt/staging_dir/target-aarch64_cortex-a53_musl/root-mediatek/stamp/.kmod-gpio-button-hotplug_installed
至此，第一个compile目标就分析完成了，接下来第二个compile主要是生成ipkg包。
3. 第二个compile分析
第二个compile代码如下：
include/package-ipkg.mk:
compile: $(PKG_INSTALL_STAMP).$(1)$(PKG_INSTALL_STAMP).$(1)依赖于prepare-package-install，prepare-package-install代码如下：
include/package-ipkg.mk:
prepare-package-install: $$(IPKG_$(1))$$(IPKG_$(1))的定义如下：
include/package-ipkg.mk:
$$(IPKG_$(1)) : export CONTROL=$$(Package/$(1)/CONTROL)
$$(IPKG_$(1)) : export DESCRIPTION=$$(Package/$(1)/description)
$$(IPKG_$(1)) : export PATH=$$(TARGET_PATH_PKG)
$$(IPKG_$(1)) : export PKG_SOURCE_DATE_EPOCH:=$(PKG_SOURCE_DATE_EPOCH)
$(PKG_INFO_DIR)/$(1).provides $$(IPKG_$(1)): $(STAMP_BUILT) $(INCLUDE_DIR)/package-ipkg.mk
@rm -rf $$(IDIR_$(1)); \
$$(call remove_ipkg_files,$(1),$$(call opkg_package_files,$(call gen_ipkg_wildcard,$(1))))
mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/CONTROL $(PKG_INFO_DIR)
$(call Package/$(1)/install,$$(IDIR_$(1)))
$(if $(Package/$(1)/install-overlay),mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/rootfs-overlay)
$(call Package/$(1)/install-overlay,$$(IDIR_$(1))/rootfs-overlay)
-find $$(IDIR_$(1)) -name 'CVS' -o -name '.svn' -o -name '.#*' -o -name '*~'| $(XARGS) rm -rf
@( \
find $$(IDIR_$(1)) -name lib\*.so\* -or -name \*.ko | awk -F/ '{ print $$$$NF }'; \
for file in $$(patsubst %,$(PKG_INFO_DIR)/%.provides,$$(IDEPEND_$(1))); do \
if [ -f "$$$$file" ]; then \
cat $$$$file; \
fi; \
done; $(Package/$(1)/extra_provides) \
) | sort -u > $(PKG_INFO_DIR)/$(1).provides
$(if $(PROVIDES),@for pkg in $(filter-out $(1),$(PROVIDES)); do cp $(PKG_INFO_DIR)/$(1).provides $(PKG_INFO_DIR)/$$$$pkg.provides; done)
$(CheckDependencies)
$(RSTRIP) $$(IDIR_$(1))
ifneq ($$(CONFIG_IPK_FILES_CHECKSUMS),)
(cd $$(IDIR_$(1)); \
( \
find . -type f \! -path ./CONTROL/\* -exec mkhash sha256 -n \{\} \; 2> /dev/null | \
sed 's|\([[:blank:]]\)\./| \1/|' > $$(IDIR_$(1))/CONTROL/files-sha256sum \
) || true \
)
endif
(cd $$(IDIR_$(1))/CONTROL; \
( \
echo "$$$$CONTROL"; \
printf "Description: "; echo "$$$$DESCRIPTION" | sed -e 's,^[[:space:]]*, ,g'; \
) > control; \
chmod 644 control; \
( \
echo "#!/bin/sh"; \
echo "[ \"\$$$${IPKG_NO_SCRIPT}\" = \"1\" ] && exit 0"; \
echo "[ -s "\$$$${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; \
echo ". \$$$${IPKG_INSTROOT}/lib/functions.sh"; \
echo "default_postinst \$$$$0 \$$$$@"; \
) > postinst; \
( \
echo "#!/bin/sh"; \
echo "[ -s "\$$$${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; \
echo ". \$$$${IPKG_INSTROOT}/lib/functions.sh"; \
echo "default_prerm \$$$$0 \$$$$@"; \
) > prerm; \
chmod 0755 postinst prerm; \
$($(1)_COMMANDS) \
)
ifneq ($$(KEEP_$(1)),)
@( \
keepfiles=""; \
for x in $$(KEEP_$(1)); do \
[ -f "$$(IDIR_$(1))/$$$$x" ] || keepfiles="$$$${keepfiles:+$$$$keepfiles }$$$$x"; \
done; \
[ -z "$$$$keepfiles" ] || { \
mkdir -p $$(IDIR_$(1))/lib/upgrade/keep.d; \
for x in $$$$keepfiles; do echo $$$$x >> $$(IDIR_$(1))/lib/upgrade/keep.d/$(1); done; \
}; \
)
endif
$(INSTALL_DIR) $$(PDIR_$(1))
$(FAKEROOT) $(SCRIPT_DIR)/ipkg-build -m "$(FILE_MODES)" $$(IDIR_$(1)) $$(PDIR_$(1))
@[ -f $$(IPKG_$(1)) ]逐行代码分析，
@rm -rf $$(IDIR_$(1)); \
$$(call remove_ipkg_files,$(1),$$(call opkg_package_files,$(call gen_ipkg_wildcard,$(1))))这句指令实际执行命令如下：
rm -rf /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug;
删除ipkg目录。
mkdir -p $(PACKAGE_DIR) $$(IDIR_$(1))/CONTROL $(PKG_INFO_DIR)实际执行命令如下：
mkdir -p /root/mt7981/openwrt/bin/targets/mediatek/mt7981/packages /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/CONTROL /root/mt7981/openwrt/staging_dir/target-aarch64_cortex-a53_musl/pkginfo
新建ipkg以及其下面的目录。
$(call Package/$(1)/install,$$(IDIR_$(1)))实际执行命令如下：
mkdir -p /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/etc/modules.d; ( echo "gpio-button-hotplug"; ) > /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/etc/modules.d/30-gpio-button-hotplug; mkdir -p /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/etc/modules-boot.d; ln -sf ../modules.d/30-gpio-button-hotplug /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/etc/modules-boot.d/;
其上面的命令都在include/kernel.mk的Package/kmod-$(1)/install中的ModuleAutoLoad实现的。
-find $$(IDIR_$(1)) -name 'CVS' -o -name '.svn' -o -name '.#*' -o -name '*~'| $(XARGS) rm -rf
@( \
find $$(IDIR_$(1)) -name lib\*.so\* -or -name \*.ko | awk -F/ '{ print $$$$NF }'; \
for file in $$(patsubst %,$(PKG_INFO_DIR)/%.provides,$$(IDEPEND_$(1))); do \
if [ -f "$$$$file" ]; then \
cat $$$$file; \
fi; \
done; $(Package/$(1)/extra_provides) \
) | sort -u > $(PKG_INFO_DIR)/$(1).provides实际执行命令如下：
find /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug -name 'CVS' -o -name '.svn' -o -name '.#*' -o -name '*~'| xargs -r rm -rf
删除掉ipkg目录下一些无关的文件。
$(RSTRIP) $$(IDIR_$(1))实际执行命令如下：
export CROSS="aarch64-openwrt-linux-musl-" NO_RENAME=1 ; NM="aarch64-openwrt-linux-musl-nm" STRIP="/root/mt7981/openwrt/staging_dir/host/bin/sstrip -z" STRIP_KMOD="/root/mt7981/openwrt/scripts/strip-kmod.sh" PATCHELF="/root/mt7981/openwrt/staging_dir/host/bin/patchelf" /root/mt7981/openwrt/scripts/rstrip.sh /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug
rstrip.sh: /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/lib/modules/5.4.203/gpio-button-hotplug.ko: relocatable
去掉ipkg中文件的符号表。
(cd $$(IDIR_$(1))/CONTROL; \
( \
echo "$$$$CONTROL"; \
printf "Description: "; echo "$$$$DESCRIPTION" | sed -e 's,^[[:space:]]*, ,g'; \
) > control; \
chmod 644 control; \
( \
echo "#!/bin/sh"; \
echo "[ \"\$$$${IPKG_NO_SCRIPT}\" = \"1\" ] && exit 0"; \
echo "[ -s "\$$$${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; \
echo ". \$$$${IPKG_INSTROOT}/lib/functions.sh"; \
echo "default_postinst \$$$$0 \$$$$@"; \
) > postinst; \
( \
echo "#!/bin/sh"; \
echo "[ -s "\$$$${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; \
echo ". \$$$${IPKG_INSTROOT}/lib/functions.sh"; \
echo "default_prerm \$$$$0 \$$$$@"; \
) > prerm; \
chmod 0755 postinst prerm; \
$($(1)_COMMANDS) \
)实际执行命令如下：
(cd /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug/CONTROL; ( echo "$CONTROL"; printf "Description: "; echo "$DESCRIPTION" | sed -e 's,^[[:space:]]*, ,g'; ) > control; chmod 644 control; ( echo "#!/bin/sh"; echo "[ \"\${IPKG_NO_SCRIPT}\" = \"1\" ] && exit 0"; echo "[ -s "\${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; echo ". \${IPKG_INSTROOT}/lib/functions.sh"; echo "default_postinst \$0 \$@"; ) > postinst; ( echo "#!/bin/sh"; echo "[ -s "\${IPKG_INSTROOT}/lib/functions.sh" ] || exit 0"; echo ". \${IPKG_INSTROOT}/lib/functions.sh"; echo "default_prerm \$0 \$@"; ) > prerm; chmod 0755 postinst prerm; )
生成ipkg下的control，postinst和prerm文件。
$(INSTALL_DIR) $$(PDIR_$(1))实际执行命令如下：
install -d -m0755 /root/mt7981/openwrt/bin/targets/mediatek/mt7981/packages
创建bin下的packages目录。
$(FAKEROOT) $(SCRIPT_DIR)/ipkg-build -m "$(FILE_MODES)" $$(IDIR_$(1)) $$(PDIR_$(1))实际执行命令如下：
/root/mt7981/openwrt/staging_dir/host/bin/fakeroot /root/mt7981/openwrt/scripts/ipkg-build -m "" /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug /root/mt7981/openwrt/bin/targets/mediatek/mt7981/packages
Packaged contents of /root/mt7981/openwrt/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/gpio-button-hotplug/ipkg-aarch64_cortex-a53/kmod-gpio-button-hotplug into /root/mt7981/openwrt/bin/targets/mediatek/mt7981/packages/kmod-gpio-button-hotplug_5.4.203-3_aarch64_cortex-a53.ipk
调用ipkg-build命令生成ipkg文件。
echo "$(1)" >> $(PKG_INSTALL_STAMP)实际执行命令如下：
echo "kmod-gpio-button-hotplug" >> /root/mt7981/openwrt/staging_dir/target-aarch64_cortex-a53_musl/pkginfo/gpio-button-hotplug.default.install
三. 总结
1. kmod的ipkg和普通的应用程序的ipkg相同点
毫无疑问，它们都必须包含ipkg的基本元素，符合ipkg的规范，有CONTROL目录，CONTROL目录下有对应的control，postinst和prerm文件，还有其他的目录，例如内核驱动有etc和lib目录，应用程序有usr目录等等。
它们都要调用include/package.mk中的BuildPackage，再调用到include/package-ipkg.mk的BuildTarget/ipkg，BuildPackage的子功能定义编译ipkg源代码的一整套流程，Prepare，Configure，Compile和Install步骤，虽然两者区别是其中一个一些步骤会省略（Build/xxx为空），例如，kmod就不需要Configure。
2. kmod的ipkg和普通的应用程序的ipkg不同点
编译kmod和普通应用的代码方式不一样。这个就体现在Build/Compile中，kmod的Makefile需要在自己的Makefile中定义这个宏，表示如何编译kmod，而应用代码Build/Compile是不推荐自定义的。
安装的方式不一样。kmod需要etc/modules.d/这样的目录，而应用程序不需要，在kmod的安装中，include/package-ipkg.mk中$(call Package/$(1)/install,$$(IDIR_$(1)))会调用到include/kernel.mk中的Package/kmod-$(1)/install，而如果再有需要，由于KernelPackage/$(1)/install定义在Package/kmod-$(1)/install，kmod的Makefile可以自定义KernelPackage/$(1)/install，做一些特殊处理。但是普通应用程序要在自己的Makefile中定义Package/$(1)/install，做一些自己需要的操作。