[PATCH] arm64: add dependency between vmlinuz.efi and Image

[Masahiro Yamada]

A common issue in Makefile is a race in parallel building.

You need to be careful to prevent multiple threads from writing to the
same file simultaneously.

Commit 3939f3345050 ("ARM: 8418/1: add boot image dependencies to not
generate invalid images") addressed such a bad scenario.

A similar symptom occurs with the following command:

  $ make -j$(nproc) ARCH=arm64 Image vmlinuz.efi
    [ snip ]
    SORTTAB vmlinux
    OBJCOPY arch/arm64/boot/Image
    OBJCOPY arch/arm64/boot/Image
    AS      arch/arm64/boot/zboot-header.o
    PAD     arch/arm64/boot/vmlinux.bin
    GZIP    arch/arm64/boot/vmlinuz
    OBJCOPY arch/arm64/boot/vmlinuz.o
    LD      arch/arm64/boot/vmlinuz.efi.elf
    OBJCOPY arch/arm64/boot/vmlinuz.efi

The log "OBJCOPY arch/arm64/boot/Image" is displayed twice.

It indicates that two threads simultaneously enter arch/arm64/boot/
and write to arch/arm64/boot/Image.

It occasionally leads to a build failure:

  $ make -j$(nproc) ARCH=arm64 Image vmlinuz.efi
    [ snip ]
    SORTTAB vmlinux
    OBJCOPY arch/arm64/boot/Image
    PAD     arch/arm64/boot/vmlinux.bin
  truncate: Invalid number: 'arch/arm64/boot/vmlinux.bin'
  make[2]: *** [drivers/firmware/efi/libstub/Makefile.zboot:13:
  arch/arm64/boot/vmlinux.bin] Error 1
  make[2]: *** Deleting file 'arch/arm64/boot/vmlinux.bin'
  make[1]: *** [arch/arm64/Makefile:163: vmlinuz.efi] Error 2
  make[1]: *** Waiting for unfinished jobs....
  make: *** [Makefile:234: __sub-make] Error 2

vmlinuz.efi depends on Image, but such a dependency is not specified
in arch/arm64/Makefile.

Signed-off-by: Masahiro Yamada <masahiroy at kernel.org>
---

 arch/arm64/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 4a1ad3248c2d..47ecc4cff9d2 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -158,7 +158,7 @@ endif
 
 all:	$(notdir $(KBUILD_IMAGE))
 
-
+vmlinuz.efi: Image
 Image vmlinuz.efi: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
-- 
2.40.1