Makefile中的$(Q)

cuer08

linux 内核中arch/arm/boot/dts/Makefile中有如下片段：

# *.dtb used to be generated in the directory above. Clean out the
# old build results so people don't accidentally use them.
dtbs: $(addprefix $(obj)/, $(dtb-y))
    $(Q)rm -f $(obj)/../*.dtb

请问这里的$(Q)是什么作用？

nswcfd

在源码树下的Makefile里有定义

1. # ---------------------------------------------------------------------------
   
2. #
   
3. # Normally, we echo the whole command before executing it. By making
   
4. # that echo $($(quiet)$(cmd)), we now have the possibility to set
   
5. # $(quiet) to choose other forms of output instead, e.g.
   
6. #
   
7. #         quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
   
8. #         cmd_cc_o_c       = $(CC) $(c_flags) -c -o $@ $<
   
9. #
   
10. # If $(quiet) is empty, the whole command will be printed.
    
11. # If it is set to "quiet_", only the short version will be printed.
    
12. # If it is set to "silent_", nothing will be printed at all, since
    
13. # the variable $(silent_cmd_cc_o_c) doesn't exist.
    
14. #
    
15. # A simple variant is to prefix commands with $(Q) - that's useful
    
16. # for commands that shall be hidden in non-verbose mode.
    
17. #
    
18. #       $(Q)ln $@ :<
    
19. #
    
20. # If KBUILD_VERBOSE equals 0 then the above command will be hidden.
    
21. # If KBUILD_VERBOSE equals 1 then the above command is displayed.
    
22. 
    
23. ifeq ($(KBUILD_VERBOSE),1)
    
24.   quiet =
    
25.   Q =
    
26. else
    
27.   quiet=quiet_
    
28.   Q = @
    
29. endif
    

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