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首页 > 解决方案 > 如何将 librt 和 libpthread 链接到 Yocto 中的新层？

linux - 如何将 librt 和 libpthread 链接到 Yocto 中的新层？

问题描述

这个问题跟
在哪里可以找到关于 aarch64-poky-linux-ld 的文档？

请忽略外部双引号集。他们似乎有必要让“StackOverflow”接受我的输入。
我的层是“meta-oca-so”，它的包是“oca”，它的配方是 oca_1.2.7.bb。
我修改了我的“oca makefile”以修复之前的和一些与无效链接标志有关的链接器错误，现在当我执行“bitbake oca”时，我可以将完整的 29 个“oca”.a 库链接在一起。在更改链接标志和重做“bitbake oca”时，我不必做任何清理工作。
现在，当我执行“bitbake oca”时，错误消息是：

~/Yocto/imx-yocto-bsp/build-wayland/tmp/work/aarch64-poky-linux/oca/1.2.7-r0/oca-1.2.7/Obj/linuxApp/Release/OcaProto
aarch64-poky-linux-ld: cannot find -lstdc++
aarch64-poky-linux-ld: cannot find -lrt
aarch64-poky-linux-ld: cannot find -lpthread
aarch64-poky-linux-ld: cannot find -ldns_sd

在这个问题中关注“librt”和“libpthread”，我将这些行添加到我的“local.conf”中：

IMAGE_INSTALL_append=" librt"
TOOLCHAIN_TARGET_TASK_append=" librt"
IMAGE_INSTALL_append=" libpthread"
TOOLCHAIN_TARGET_TASK_append=" libpthread"

但是当我重做“bitbake oca”时，它并没有清除它的两个链接错误。

当我尝试整体“bitbake imx-image-multimedia”时，我收到了关于“librt”的这些消息：

NOTE: Resolving any missing task queue dependencies
ERROR: Nothing RPROVIDES 'librt' (but /home/james/Yocto/imx-yocto-bsp/sources/meta-imx/meta-sdk/recipes-fsl/images/imx-image-multimedia.bb RDEPENDS on or otherwise requires it)
NOTE: Runtime target 'librt' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['librt']
ERROR: Required build target 'imx-image-multimedia' has no buildable providers.
Missing or unbuildable dependency chain was: ['imx-image-multimedia', 'librt']

很难找到关于“rt”的很多信息，因为这个两个字母的组合在统计上并非不可能。

同样，当我从“local.conf”中注释掉两个“librt”行并重试“bitbake imx-image-multimedia”时，我收到了关于“libpthread”的这些消息：

ERROR: Nothing RPROVIDES 'libpthread' (but /home/james/Yocto/imx-yocto-bsp/sources/meta-imx/meta-sdk/recipes-fsl/images/imx-image-multimedia.bb RDEPENDS on or otherwise requires it)
NOTE: Runtime target 'libpthread' is unbuildable, removing...
Missing or unbuildable dependency chain was: ['libpthread']
ERROR: Required build target 'imx-image-multimedia' has no buildable providers.
Missing or unbuildable dependency chain was: ['imx-image-multimedia', 'libpthread']

如何获得“librt”和“libpthread”？
我需要每个添加一个图层来构建它们吗？每个人都需要支持包的“依赖地狱”树吗？

这是相关的makefile 组件makeOCA.inc。OCA项目中有63个不同描述、不同级别的“make”文件。它很长，大约 1070 行。我剪掉了非 Linux 系统的部分；我只关心这里的 linuxRelease。

#  Project             : OCA
#  Module              : Multiple components
#  Description         : Include file for C / CPP makefiles.
#

################################################################################
# Environment variable checking
################################################################################
#
# If one of the variables below is not set,
# calling make will result in a "missing separator" error.
#
ifeq ($(CAP_HOME),)
  variable CAP_HOME is not set
else
  CAP_HOME := $(patsubst %/,%,$(subst \,/,$(CAP_HOME)))
endif

################################################################################
# Variables
################################################################################
ifeq ($(NAME_MKE),)
  NAME_MKE := makefileOCA
endif
ifeq ($(IGNORE_MAKE_ERRORS),Y)
  PREFIX := -@
else
  ifneq ($(DISPLAY_MAKE_CMDS),Y)
    PREFIX := @
  endif
endif
EMPTY :=
SPACE := $(EMPTY) $(EMPTY)
#
# Only set variables when the makefile is called with an actual target
# (not a phony one).
#
ifneq ($(PLATFORM),)
  ifneq ($(RELEASE),)

    # Project home
    PRJ_HOME := $(CAP_HOME)

    # Src home
    SRC_HOME := $(PRJ_HOME)/Src

    # Include directories
    ifneq ($(USRINC),)
    INCDIRS := $(subst ; ,;,$(subst \,/,.;\
        $(SRC_HOME)/inc;\
        $(SRC_HOME)/lib/inc;\
        $(SRC_HOME)/common;\
        $(SRC_HOME)/common/OCA;\
        $(SRC_HOME)/common/HostInterface;\
        $(SRC_HOME)/platform;\
        $(SRC_HOME)/platform/common;\
        $(SRC_HOME)/adamson;\
        $(USRINC)))
    else
    INCDIRS := $(subst ; ,;,$(subst \,/,.;\
        $(SRC_HOME)/inc;\
        $(SRC_HOME)/lib/inc;\
        $(SRC_HOME)/common;\
        $(SRC_HOME)/common/OCA;\
        $(SRC_HOME)/common/HostInterface;\
        $(SRC_HOME)/platform;\
        $(SRC_HOME)/platform/common;\
        $(SRC_HOME)/adamson))
    endif

    # Output directories
    OBJDIR := Obj
    OBJINT := intermediate
    OUTDIR := $(subst \,/,$(PRJ_HOME))/$(OBJDIR)/$(PLATFORM)/$(RELEASE)
    ifeq ($(GINTDIR),)
        GINTDIR := $(OUTDIR)/$(OBJINT)
    endif
    INTDIR := $(GINTDIR)/$(NAME)

    # Tools
    SD := CC -M -MP -march=native
    SE := sed
    RC :=
    ifeq ($(OS),Windows_NT)
        RM := erase /F
        MD := mkdir
        RN := ren _PATH__OLDNAME_ _NEWNAME_
        RD := rd /s/q
    else
        RM := rm -f
        MD := mkdir -p
        RN := mv _PATH__OLDNAME_ _PATH__NEWNAME_
        RD := rm -rf
    endif

    # Commands
    ifeq ($(OS),Windows_NT)
        IFEXIST    := if exist _FILE_ _COMMAND_
        IFNOTEXIST := if not exist _FILE_ _COMMAND_
    else
        IFEXIST    := if [ -e "_FILE_" ]; then _COMMAND_; fi
        IFNOTEXIST := if [ ! -e "_FILE_" ]; then _COMMAND_; fi
    endif

    # Other OS dependent variables
    # Work around to make sure only a single backslash is set
    ifeq ($(OS),Windows_NT)
        PATH_SEP := $(subst \\,\,\\)
    else
        PATH_SEP := $(subst \\,/,/)
    endif

    ifeq ($(PLATFORM),winntApp)

      CXXFLAGS :=
      RCFLAGS := -I "$(subst ;," -I ",$(INCDIRS))"


### linuxRelease ###############################################################

      ifeq ($(RELEASE),Release)

        # Tools
        # CC := gcc

        # Determine the extensions for the target platform
        OBJ_EXT := o
        DEP_EXT := dep
        EXE_EXT :=
        LIB_EXT := a
        DLL_EXT := so

        # Lists
        OBJS := $(patsubst %.cpp,%.$(OBJ_EXT),$(SRCS) $(LINUXSRCS))
        OBJS := $(patsubst %.c,%.$(OBJ_EXT),$(OBJS))
        DEPS := $(patsubst %.$(OBJ_EXT),%.$(DEP_EXT),$(OBJS))
        LIBS := $(LIBS) $(LINUXLIBS) $(EXTERNAL_LIBS)
        LIBS := $(addsuffix .$(LIB_EXT), $(LIBS))
        LIBS := $(addprefix $(OUTDIR)/, $(LIBS))

        SDFLAGS := -O2 -nostdlib -fno-strict-aliasing -ffunction-sections -fdata-sections -c -Wall -Wno-unknown-pragmas -x none \
                   -I"$(subst ;," -I",$(INCDIRS))" \
                   -D"NDEBUG" -DTARGET_LINUX -D"CPPUNIT_TUI_VERSION" -D"__STDC_FORMAT_MACROS" \
                   $(foreach USRDEF,$(USRDEFS),-D"$(USRDEF)") \
                   $(foreach USRUNDEF,$(USRUNDEFS),-U"$(USRUNDEF)")
        SDCFLAGS :=
        SDCPPFLAGS := -std=c++0x
        CCFLAGS = $(SDFLAGS) -fexceptions -fvisibility=hidden -march=armv8-a -mtune=cortex-a53 -o $(INTDIR)/$@
# That's for Linaro and the Snapdragon410 (Qualcomm APQ8016) processor; next is for Ubuntu 18.04.1
#       CCFLAGS = $(SDFLAGS) -fexceptions -fvisibility=hidden -m64 -mtune=generic -o $(INTDIR)/$@
        CXXFLAGS := -std=gnu++0x

        ifeq ($(TYPE),EXE)
          OUT_EXT := $(EXE_EXT)
          # LD := gcc
          LD := aarch64-poky-linux-ld
#         LDFLAGS = -Wl,--gc-sections -fno-keep-static-consts -fexceptions -march=armv8-a -maarch64linux -L$(OUTDIR) -o$@
# Use the above -Wl when using gcc. When using ld directly, it doesn't take -Wl. aarch64-poky-linux-ld doesn't have the -f options.
          LDFLAGS = --gc-sections -march=armv8-a -maarch64linux -L$(OUTDIR) -o$@
# That's for Linaro and the Snapdragon410 (Qualcomm APQ8016) processor; next is for Ubuntu 18.04.1
#         LDFLAGS = -Wl,--gc-sections -fno-keep-static-consts -fexceptions -m64 -mtune=x86-64 -L$(OUTDIR) -o$@
          LINUXSYSTEMLIBS := -lstdc++ -lrt -lpthread $(addprefix -l, $(LINUXSYSTEMLIBS))
        endif
        ifeq ($(TYPE),LIB)
          OUT_EXT := $(LIB_EXT)
          # LD := ar
          LDFLAGS = crus $@
        endif
        ifeq ($(TYPE),DLL)
          OUT_EXT := $(DLL_EXT)
          # LD := gcc
          LD := aarch64-poky-linux-ld
#         LDFLAGS = -Wl,--gc-sections -export-dynamic -fno-keep-static-consts -fexceptions -march=armv8-a -maarch64linux -L$(OUTDIR) -o$@
# Use the above -Wl when using gcc. When using ld directly, it doesn't take -Wl. aarch64-poky-linux-ld doesn't have the -f options.
          LDFLAGS = --gc-sections -export-dynamic -march=armv8-a -maarch64linux -L$(OUTDIR) -o$@
# That's for Linaro and the Snapdragon410 (Qualcomm APQ8016) processor; next is for Ubuntu 18.04.1
#         LDFLAGS = -Wl,--gc-sections -export-dynamic -fno-keep-static-consts -fexceptions -m64 -mtune=x86-64 -L$(OUTDIR) -o$@
          LINUXSYSTEMLIBS := -lstdc++ -lrt -lpthread $(addprefix -l, $(LINUXSYSTEMLIBS))
        endif
      endif

    endif #ifeq ($(PLATFORM),linuxApp)

  endif #ifneq ($(RELEASE),)
endif #ifneq ($(PLATFORM),)

################################################################################
# Phony target specification
################################################################################
.PHONY: goal all clean phonyclean $(NAME)\
        winntDebug winntRelease \
        winntDebug64 winntRelease64 \
        winntDebugClean winntReleaseClean \
        winntDebug64Clean winntRelease64Clean \
        linuxDebug linuxRelease \
        linuxDebugClean linuxReleaseClean

################################################################################
# Targets
################################################################################
goal: winntDebug winntRelease

all: winntDebug winntRelease \
     winntDebug64 winntRelease64

clean: winntDebugClean winntReleaseClean \
       winntDebug64Clean winntRelease64Clean

linuxRelease:
  ifneq (,$(findstring linux,$(TARGETS)))
    $(PREFIX)$(MAKE) -f $(NAME_MKE) $(NAME) --no-print-directory PLATFORM=linuxApp RELEASE=Release
  else
    $(PREFIX)echo $@ not configured for $(NAME)
  endif

linuxReleaseClean:
  ifneq (,$(findstring linux,$(TARGETS)))
    $(PREFIX)$(MAKE) -f $(NAME_MKE) phonyclean --no-print-directory PLATFORM=linuxApp RELEASE=Release CLEAN=Yes
  else
    $(PREFIX)echo linuxRelease not configured for $(NAME)
  endif

### Dependency files ###########################################################

$(INTDIR)/%.$(DEP_EXT) : %.c
    $(PREFIX)echo $(@F)
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$@),$(subst _COMMAND_,$(RM) $(subst /,$(PATH_SEP),$@),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$@.tmp),$(subst _COMMAND_,$(RM) $(subst /,$(PATH_SEP),$@.tmp),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(GINTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(GINTDIR)),$(IFNOTEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(INTDIR)),$(IFNOTEXIST)))
  #
  # Do not use (OBJ_EXT) in the SED command, since all dependencies are generated with gcc.
  # Use .o instead
  #
    $(PREFIX)$(SD) $(SDCFLAGS) $(SDFLAGS) $< | $(SE) "s/$*.o:/$*.$(OBJ_EXT) $(subst /,\/,$@):/" > $(subst /,$(PATH_SEP),$@.tmp)
    $(PREFIX)$(subst _PATH_,$(subst /,$(PATH_SEP),$(INTDIR)/),$(subst _OLDNAME_,$(@F).tmp,$(subst _NEWNAME_,$(@F),$(RN))))

$(INTDIR)/%.$(DEP_EXT) : %.cpp
    $(PREFIX)echo $(@F)
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$@),$(subst _COMMAND_,$(RM) $(subst /,$(PATH_SEP),$@),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$@.tmp),$(subst _COMMAND_,$(RM) $(subst /,$(PATH_SEP),$@.tmp),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(GINTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(GINTDIR)),$(IFNOTEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(INTDIR)),$(IFNOTEXIST)))
  #
  # Do not use (OBJ_EXT) in the SED command, since all dependencies are generated with gcc.
  # Use .o instead
  #
    $(PREFIX)$(SD) $(SDCPPFLAGS) $(SDFLAGS) $< | $(SE) "s/$*.o:/$*.$(OBJ_EXT) $(subst /,\/,$@):/" > $(subst /,$(PATH_SEP),$@.tmp)
    $(PREFIX)$(subst _PATH_,$(subst /,$(PATH_SEP),$(INTDIR)/),$(subst _OLDNAME_,$(@F).tmp,$(subst _NEWNAME_,$(@F),$(RN))))

### Object files ###############################################################

%.$(OBJ_EXT) : %.asm
    $(PREFIX)echo $(@F)
    $(PREFIX)$(AS) $(ASFLAGS) $<

%.$(OBJ_EXT) : %.S
    $(PREFIX)echo $(@F)
    $(PREFIX)$(AS) $(ASFLAGS) $<

%.$(RES_EXT) : %.rc
    $(PREFIX)echo $(@F)
    $(PREFIX)"$(RC)" $(RCFLAGS) -fo "$(INTDIR)/$(@F)" $<

%.$(OBJ_EXT) : %.c $(TOOL_DEPS)
  ifneq ($(CC),cl.exe)
    $(PREFIX)echo $(@F)
  endif
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)/$@),$(subst _COMMAND_,$(RM) $(subst /,$(PATH_SEP),$(INTDIR)/$@),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(INTDIR)),$(IFNOTEXIST)))
    $(PREFIX)$(CC) $(CCFLAGS) $<

%.$(OBJ_EXT) : %.cpp $(TOOL_DEPS)
  ifneq ($(CC),cl.exe)
    $(PREFIX)echo $(@F)
  endif
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)/$@),$(subst _COMMAND_,$(RM) $(subst /,$(PATH_SEP),$(INTDIR)/$@),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(INTDIR)),$(IFNOTEXIST)))
    $(PREFIX)$(CC) $(CCFLAGS) $(CXXFLAGS) $<

### Output file ################################################################

$(NAME): $(OUTFILE) $(BINFILE)

$(OUTFILE): $(INTDIR)/$(NAME).x $(OBJS) $(LIBS) $(NAME_MKE)
    $(PREFIX)echo $@
    $(PREFIX)$(subst _FILE_,$@,$(subst _COMMAND_,$(RM) $@,$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(OUTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(OUTDIR)),$(IFNOTEXIST)))
    ifneq (,$(findstring $(OBJINT),$(OBJS)))
        $(foreach obj,$(OBJS),$(shell echo $(obj) >> $(LSTFILE)))
    else
        $(foreach obj,$(OBJS),$(shell echo $(subst /,$(PATH_SEP),$(INTDIR)/$(obj)) >> $(LSTFILE)))
    endif
    ifneq (,$(filter $(PLATFORM),linuxApp))
      ifeq ($(TYPE),LIB)    
    $(PREFIX)ar $(LDFLAGS) @$(LSTFILE) $(LIBS) $(LINUXSYSTEMLIBS)
      else
        ifeq ($(TYPE),EXE)    
        $(PREFIX)aarch64-poky-linux-ld $(LDFLAGS) @$(LSTFILE) $(LIBS) $(LINUXSYSTEMLIBS)
        else
          ifeq ($(TYPE),DLL)    
        $(PREFIX)aarch64-poky-linux-ld $(LDFLAGS) @$(LSTFILE) $(LIBS) $(LINUXSYSTEMLIBS)
          else
        $(PREFIX)LD $(LDFLAGS) @$(LSTFILE) $(LIBS) $(LINUXSYSTEMLIBS)
          endif
        endif
      endif
    else
      ifeq ($(PLATFORM),winntApp)
        $(PREFIX)$(LD) $(LDFLAGS) @$(LSTFILE) $(WINNTSYSTEMLIBS)
      else
        $(PREFIX)$(LD) $(LDFLAGS) @$(LSTFILE)
      endif
    endif
    $(PREFIX)$(subst _FILE_,$(LSTFILE),$(subst _COMMAND_,$(RM) $(LSTFILE),$(IFEXIST)))

$(BINFILE): $(OUTFILE)
    $(PREFIX)echo $@
    $(PREFIX)$(B2B) $(B2BFLAGS) $(OUTFILE) $(BINFILE)

$(INTDIR)/$(NAME).x:
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)),$(subst _COMMAND_,$(MD) $(subst /,$(PATH_SEP),$(INTDIR)),$(IFNOTEXIST)))
    $(PREFIX)echo Checkpoint file for component $(NAME) > $(subst /,$(PATH_SEP),$@)

### Clean ######################################################################

phonyclean:
  ifneq ($(PLATFORM),)
    ifneq ($(RELEASE),)
    $(PREFIX)$(subst _FILE_,$(subst /,$(PATH_SEP),$(INTDIR)),$(subst _COMMAND_,$(RD) $(subst /,$(PATH_SEP),$(INTDIR)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(patsubst %.$(OUT_EXT),%.pdb,$(OUTFILE)),$(subst _COMMAND_,$(RM) $(patsubst %.$(OUT_EXT),%.pdb,$(OUTFILE)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(patsubst %.$(OUT_EXT),%.map,$(OUTFILE)),$(subst _COMMAND_,$(RM) $(patsubst %.$(OUT_EXT),%.map,$(OUTFILE)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(patsubst %.$(OUT_EXT),%.dat,$(OUTFILE)),$(subst _COMMAND_,$(RM) $(patsubst %.$(OUT_EXT),%.dat,$(OUTFILE)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(patsubst %.$(OUT_EXT),%.exp,$(OUTFILE)),$(subst _COMMAND_,$(RM) $(patsubst %.$(OUT_EXT),%.exp,$(OUTFILE)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(patsubst %.$(OUT_EXT),%.lib,$(OUTFILE)),$(subst _COMMAND_,$(RM) $(patsubst %.$(OUT_EXT),%.lib,$(OUTFILE)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(patsubst %.$(OUT_EXT),%.err,$(OUTFILE)),$(subst _COMMAND_,$(RM) $(patsubst %.$(OUT_EXT),%.err,$(OUTFILE)),$(IFEXIST)))
    $(PREFIX)$(subst _FILE_,$(OUTFILE),$(subst _COMMAND_,$(RM) $(OUTFILE),$(IFEXIST)))
    else
    $(PREFIX)echo Target $@ should not be used from command line
    endif
  else
    $(PREFIX)echo Target $@ should not be used from command line
  endif

################################################################################
# Include dependency files
################################################################################
ifneq ($(PLATFORM),)
  ifneq ($(RELEASE),)
    #
    # If cleaning, we must not include dependency files.
    # Otherwise they will be created before cleaning.
    #
    ifeq ($(CLEAN),)
      ifeq (,$(findstring $(OBJINT),$(OBJS)))
        #
        # Use a - in front of the include, otherwise make will complain
        # when it is ran the first time (when there are no .dep files).
        #
        -include $(patsubst %.$(DEP_EXT),$(INTDIR)/%.$(DEP_EXT),$(DEPS))
      endif
    endif
  endif
endif

有人可以指出一个完整的 Yocto 层的简单示例，包括生成文件和交叉编译的简单代码吗？对我来说似乎很难找到，尤其是支持在交叉编译中使用的makefile。

一个重要的认识是文档是关于 CFLAGS 和 LDFLAGS 的路径变量和其他设置的：在 Yocto 大型手册中的所有变量，在“第 33 章。变量词汇表”，https://www.yoctoproject.org/ docs/3.0/mega-manual/mega-manual.html#ref-variables-glos

标签： linuxyocto

解决方案

Yocto 依赖概念

首先，您似乎在 Yocto 中混合了各种依赖概念：

  • IMAGE_INSTALL是一个图像依赖项，告诉 Yocto 参数中的配方必须安装在最终图像中。它应该放在图像配方中，而不是包装配方中。我不认为将它添加到包配方中会告诉 Yocto 将此依赖项添加到配方的暂存目录中。
  • RDEPENDS在包配方中使用，并告诉 Yocto 配方取决于运行时参数中的包。然后，如果您安装需要它们的包，它将在最终映像中安装所需的运行时依赖项。
    一个基本示例是包含脚本 shell 的配方在运行时依赖于某些 shell 解释器。
  • DEPENDS也在包配方中使用，并告诉 Yocto 配方取决于编译时参数中的包。它将在配方的暂存目录中添加头文件和库。

话虽如此libstdc++，libpthread和librt是工具链的一部分，您无需为此在配方中添加显式依赖项。它们将毫不费力地安装在暂存目录或您的配方中。

关于libdns_sd，经过我的快速研究，这个库是由 mDNS 提供的。然后，您需要添加对它的依赖项：

DEPENDS = "mdns"

如上所述，这将在配方的暂存目录中添加头文件 *.a 和 *.so。

什么不见​​了 ？

一旦正确配置了依赖项，您的编译器需要知道包含和库目录在哪里，而 Makefile 中显然缺少这可能是因为您假设依赖项是主机工具链的一部分。当您直接为主机构建时，编译器知道在哪里可以找到包含（例如在 /usr/include 中搜索）和库，这使得这个过程变得非常简单。

但是，对于标准交叉编译项目，在 Yocto 中，头文件和库位于其他位置，您需要在 Makefile 中正确指定。

在 Yocto 中管理 Makefile 项目有多种可能性，但在所有情况下，您都需要一个可以接收变量（CFLAGS、LDFLAGS 等）或可选参数的 Makefile，以便在从您的配方调用时传递给编译器/链接器。

由于您不提供 Yocto 食谱，我将举例说明如何完成并提出一些建议。此外，我专注于编译方面，该示例并不完整，可能应该适用于其他构建步骤（如安装）。

DEPENDS += "my-extralib"

# Change eventually the default source directory
S = "${WORKDIR}/git"

EXTRA_OEMAKE = " 'CC=${CC}' \
    'CFLAGS=${CFLAGS} ${TARGET_CC_ARCH} -I${S}/inc -I${STAGING_DIR_TARGET}${includedir}/my-extralib-include' \
    'LDFLAGS=-lrt -lpthread -lm -lmy-extralib -L${STAGING_DIR_TARGET}${libdir}/my-extralib-libdir' \
    'BUILDDIR=${S}' \
    'OTHER_DEFINE=${OTHER_YOCTO_VAR}' \
"

使用 EXTRA_OEMAKE 可以让 Yocto 自动为您完成许多任务，例如配置、编译和安装。如果你想覆盖它们，这也是可能的：

do_compile() {
    # modify the Makefile on the fly as an example
    cp ${S}/Makefile.orig ${S}/Makefile
    sed -i -e 's:= $(LDFLAGS):?= $(LDFLAGS):' ${S}/Makefile
    oe_runmake SOME_OVERRIDE='some-override'
}

您还可以禁用可能未在您的情况下使用的配置步骤：

do_configure[noexec] = "1"

一些技巧

  • 如果你从 Yocto 开始，有很多东西要学，而且一开始很难找到如何管理所有可能性和选项。我强烈建议您从一个简单的 Makefile 和最少的源文件开始，以专注于 Yocto 方面。
  • 您可以在网络上找到很多食谱示例（还有 Yocto、Poky 基础食谱），这些示例可能与您正在努力实现的目标很接近。Yocto 的文档确实很完整，但它更像是一个基础参考。具体的实现可以在现有的配方中找到。
  • 配方构建目录中的临时目录是一个金矿，其中包含不同构建步骤的所有脚本和日志。这是您创建食谱时首先要看的地方。

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