From e41b93a6be57e26a4a123345f826a6ac3a213551 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Mon, 3 Dec 2018 19:55:55 +1100
Subject: [PATCH] powerpc/boot: Fix build failures with -j 1

References: bsc#1065729
Patch-mainline: v4.20-rc7
Git-commit: e41b93a6be57e26a4a123345f826a6ac3a213551

In commit 5e9dcb6188a4 ("powerpc/boot: Expose Kconfig symbols to
wrapper") we added a dependency to serial.c on autoconf.h:

  $(obj)/serial.c: $(obj)/autoconf.h

This works when building in-tree (ie. with KBUILD_OUTPUT unset)
because the obj tree is the src tree.

But when building with eg. O=build and -j 1 the build fails:

  gcc ... -I../arch/powerpc/boot -c -o arch/powerpc/boot/serial.o arch/powerpc/boot/serial.c
  gcc: error: arch/powerpc/boot/serial.c: No such file or directory

Why this is only happening with -j 1 is not clear, when building with
-j greater than 1 somehow we decide to look for serial.c in the src
tree (../), eg:

  gcc -I../arch/powerpc/boot -c -o arch/powerpc/boot/serial.o ../arch/powerpc/boot/serial.c

Regardless we shouldn't be specifying a dependency on serial.c in the
build tree, we want to add a dependency to the version in $(srctree)
so fix the rule to say that.

Fixes: 5e9dcb6188a4 ("powerpc/boot: Expose Kconfig symbols to wrapper")
Tested-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/boot/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index 39354365f54a..ed9883169190 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -197,7 +197,7 @@ $(obj)/empty.c:
 $(obj)/zImage.coff.lds $(obj)/zImage.ps3.lds : $(obj)/%: $(srctree)/$(src)/%.S
 	$(Q)cp $< $@
 
-$(obj)/serial.c: $(obj)/autoconf.h
+$(srctree)/$(src)/serial.c: $(obj)/autoconf.h
 
 $(obj)/autoconf.h: $(obj)/%: $(objtree)/include/generated/%
 	$(Q)cp $< $@
-- 
2.19.2