Re: [PATCH] Kbuild: Avoid DTB rebuilds if source files are untouched

[Stephen Warren <swarren@wwwdotorg.org>]

On 04/12/2013 01:40 AM, Vineet Gupta wrote:
> On 04/09/2013 07:40 PM, Vineet Gupta wrote:
>> On 04/04/2013 11:06 PM, Stephen Warren wrote:
>>
>>> +.SECONDARY: $(obj)/%.dtb.S
>>> +
>>>  $(obj)/%.dtb.S: $(obj)/%.dtb
>>>         $(call cmd,dt_S_dtb)
>>>
>>> and no longer see make rm'ing the .dtb.S file. So, the .SECONDARY is
>>> behaving as expected, and should fix your problem.
>> Interestingly, if I make the file name explicit, .SECONDARY works for me too.
>>
>> .SECONDARY: $(obj)/angel4.dtb.S
>>
>> http://stackoverflow.com/questions/5426934/why-this-makefile-removes-my-goal
>>
>> Is this a make bug or is it related to when the rule is parsed by make !
>>
>> -Vineet
> 
> Ping ? Anyone know how to resolve this

After installing the ARC toolchain (which was a bit painful to track
down and install...) I reproduced your exact problem. I believe the
patch below fixes it:

diff --git a/arch/arc/boot/dts/Makefile b/arch/arc/boot/dts/Makefile
index 5776835..2f2cf23 100644
--- a/arch/arc/boot/dts/Makefile
+++ b/arch/arc/boot/dts/Makefile
@@ -8,6 +8,8 @@ endif
 obj-y   += $(builtindtb-y).dtb.o
 targets += $(builtindtb-y).dtb

+.SECONDARY: $(obj)/$(builtindtb-y).dtb.S
+
 dtbs:  $(addprefix  $(obj)/, $(builtindtb-y).dtb)

 clean-files := *.dtb