在内核makefile $(call cmd，tags)中，这里的cmd是指什么? [英] In Kernel makefile $(call cmd, tags) what is the cmd here refers to?

问题描述

在内核Makefile中，我找到了如下代码:

In Kernel Makefile i found the code like below:

ctags CTAGS CSCOPE: $(HEADERS) $(SOURCES) 

$(ETAGS) $(ETAGSFALGS) $(HEADERS) $(SOURCES)

$(call cmd, ctags)

此外，我在哪里可以找到宏或函数?

Also, where can i find the Macro or function ?

推荐答案

在内核v4.1上使用MadScientist的方法:

Using MadScientist's method on kernel v4.1:

make -p | grep -B1 -E '^cmd '

我们发现:

# makefile (from `scripts/Kbuild.include', line 211)
cmd = @$(echo-cmd) $(cmd_$(1))

scripts/Kbuild.include包含在顶层Makefile中.它还包含:

scripts/Kbuild.include is included on the top level Makefile. It also contains:

echo-cmd = $(if $($(quiet)cmd_$(1)),\
    echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)

• quiet:根据V的值设置在顶层makefile中.

  • quiet: set at the top level makefile, depending on the value of V.

    将是:

    • quiet_打印CC file.c
    • 空以在V=
    上打印命令
    • silent_不能在make -s
    上打印任何内容
    • quiet_ to print CC file.c
    • empty to print the command on V=
    • silent_ to not print anything on make -s

    escsq定义为:

    squote  := '
    escsq = $(subst $(squote),'\$(squote)',$1)
    

    它转义单引号，以便echo '$(call escsq,Letter 'a'.'可以在sh中正确打印.

    It escapes single quotes so that echo '$(call escsq,Letter 'a'.' will print properly in sh.

    echo-why:在Kbuild.include处进一步定义.

    它用于make V=2，并说明了为什么要重制目标.

    It is used for make V=2, and says why a target is being remade.

    make tags的设置在Makefile中完成:

    quiet_cmd_tags = GEN     $@
          cmd_tags = $(CONFIG_SHELL) $(srctree)/scripts/tags.sh $@
    
    tags TAGS cscope gtags: FORCE
        $(call cmd,tags)
    

    其中显示了在kbuild上调用命令的典型用法模式:

    Which shows the typical usage pattern for calling commands on kbuild:

    quiet_cmd_XXX = NAME     $@
          cmd_XXX = actual-command $@
    
    target: prerequisites
        $(call cmd,tags)
    

    对Makefile的注释说明了如何完成所有这些操作以使make输出更漂亮:

    A comment on the Makefile explains how all of this is done to make the make output prettier:

    # Beautify output
    # ---------------------------------------------------------------------------
    #
    # Normally, we echo the whole command before executing it. By making
    # that echo $($(quiet)$(cmd)), we now have the possibility to set
    # $(quiet) to choose other forms of output instead, e.g.
    #
    #         quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
    #         cmd_cc_o_c       = $(CC) $(c_flags) -c -o $@ $<
    

    这篇关于在内核makefile $(call cmd，tags)中，这里的cmd是指什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！