From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 16 Apr 2013 03:13:58 +0000 (+0530)
Subject: ARC: [kbuild] Avoid DTB rebuilds if DTS are untouched
X-Git-Tag: v3.10-rc1~25^2~22
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a89516b31c8c0a41b4955fbcee764901232d71b1;p=pandora-kernel.git

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>
---

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