ARC: [kbuild] Avoid DTB rebuilds if DTS are untouched
authorVineet Gupta <vgupta@synopsys.com>
Tue, 16 Apr 2013 03:13:58 +0000 (08:43 +0530)
committerVineet Gupta <vgupta@synopsys.com>
Wed, 17 Apr 2013 12:49:14 +0000 (18:19 +0530)
commita89516b31c8c0a41b4955fbcee764901232d71b1
tree13bdad5cbd13a59679e39347b1ac695a85f4e66f
parent5628832f4c2c2604d5c99f3c2ff8aa73b0b121b8
ARC: [kbuild] Avoid DTB rebuilds if DTS are untouched

Currently, for every ARC kernel build I see the following:

--------------->8-----------------
  DTB    arch/arc/boot/dts/angel4.dtb.S
  AS      arch/arc/boot/dts/angel4.dtb.o
  LD      arch/arc/boot/dts/built-in.o
rm arch/arc/boot/dts/angel4.dtb.S        <-- forces rebuild next iter
  CHK     kernel/config_data.h
--------------->8-----------------

This is because *.dts.S is intermediate file in dtb generation and is by
default deleted by make which needs a ".SECONDARY" hint to NOT do so.

This could have ideally been done in scripts/Makefile.lib - for benefit
of all, however .SECONDARY doesn't seem to work with wildcards.

Thanks to Stephen for suggesting .SECONDARY (vs .PRECIOUS) and making
that work using a non wildcard version in arch makefile.

Thanks to James Hogan for pointing out that *.dtb.S now needs to be
added to clean-files

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
arch/arc/boot/dts/Makefile