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From:   Masahiro Yamada <masahiroy@kernel.org>
To:     Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>, loongarch@lists.linux.dev
Cc:     linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Simon Glass <sjg@chromium.org>,
        Masahiro Yamada <masahiroy@kernel.org>
Subject: [PATCH] loongarch: add dependency between vmlinuz.efi and vmlinux.efi
Date:   Sun, 19 Nov 2023 14:34:48 +0900
Message-Id: <20231119053448.2367725-1-masahiroy@kernel.org>
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Precedence: bulk

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=loongarch vmlinux.efi vmlinuz.efi
    [ snip ]
    SORTTAB vmlinux
    OBJCOPY arch/loongarch/boot/vmlinux.efi
    OBJCOPY arch/loongarch/boot/vmlinux.efi
    PAD     arch/loongarch/boot/vmlinux.bin
    GZIP    arch/loongarch/boot/vmlinuz
    OBJCOPY arch/loongarch/boot/vmlinuz.o
    LD      arch/loongarch/boot/vmlinuz.efi.elf
    OBJCOPY arch/loongarch/boot/vmlinuz.efi

The log "OBJCOPY arch/loongarch/boot/vmlinux.efi" is displayed twice.

It indicates that two threads simultaneously enter arch/loongarch/boot/
and write to arch/loongarch/boot/vmlinux.efi.

It occasionally leads to a build failure:

  $ make -j$(nproc) ARCH=loongarch vmlinux.efi vmlinuz.efi
    [ snip ]
    SORTTAB vmlinux
    OBJCOPY arch/loongarch/boot/vmlinux.efi
    PAD     arch/loongarch/boot/vmlinux.bin
  truncate: Invalid number: ‘arch/loongarch/boot/vmlinux.bin’
  make[2]: *** [drivers/firmware/efi/libstub/Makefile.zboot:13:
  arch/loongarch/boot/vmlinux.bin] Error 1
  make[2]: *** Deleting file 'arch/loongarch/boot/vmlinux.bin'
  make[1]: *** [arch/loongarch/Makefile:146: vmlinuz.efi] Error 2
  make[1]: *** Waiting for unfinished jobs....
  make: *** [Makefile:234: __sub-make] Error 2

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

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

 arch/loongarch/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 9eeb0c05f3f4..6022bf3d30c9 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -142,6 +142,7 @@ vdso-install-y += arch/loongarch/vdso/vdso.so.dbg
 
 all:	$(notdir $(KBUILD_IMAGE))
 
+vmlinuz.efi: vmlinux.efi
 vmlinux.elf vmlinux.efi vmlinuz.efi: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(bootvars-y) $(boot)/$@
 
-- 
2.40.1