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References: <20231119100024.2370992-1-masahiroy@kernel.org>
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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Tue, 21 Nov 2023 11:36:48 -0500
Message-ID: <CAMj1kXF5Vm+Br68qk3rxgtsUxTknz2stfBTpruwQ3diVQrAc3Q@mail.gmail.com>
Subject: Re: [PATCH v2] riscv: add dependency among Image(.gz), loader(.bin),
 and vmlinuz.efi
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-kbuild@vger.kernel.org, Simon Glass <sjg@chromium.org>
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On Sun, 19 Nov 2023 at 05:00, Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> 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=riscv Image Image.gz loader loader.bin vmlinuz.efi
>     [ snip ]
>     SORTTAB vmlinux
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     GZIP    arch/riscv/boot/Image.gz
>     AS      arch/riscv/boot/loader.o
>     AS      arch/riscv/boot/loader.o
>     Kernel: arch/riscv/boot/Image is ready
>     PAD     arch/riscv/boot/vmlinux.bin
>     GZIP    arch/riscv/boot/vmlinuz
>     Kernel: arch/riscv/boot/loader is ready
>     OBJCOPY arch/riscv/boot/loader.bin
>     Kernel: arch/riscv/boot/loader.bin is ready
>     Kernel: arch/riscv/boot/Image.gz is ready
>     OBJCOPY arch/riscv/boot/vmlinuz.o
>     LD      arch/riscv/boot/vmlinuz.efi.elf
>     OBJCOPY arch/riscv/boot/vmlinuz.efi
>     Kernel: arch/riscv/boot/vmlinuz.efi is ready
>
> The log "OBJCOPY arch/riscv/boot/Image" is displayed 5 times.
> (also "AS      arch/riscv/boot/loader.o" twice.)
>
> It indicates that 5 threads simultaneously enter arch/riscv/boot/
> and write to arch/riscv/boot/Image.
>
> It occasionally leads to a build failure:
>
>   $ make -j$(nproc) ARCH=riscv Image Image.gz loader loader.bin vmlinuz.efi
>     [ snip ]
>     SORTTAB vmlinux
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     OBJCOPY arch/riscv/boot/Image
>     PAD     arch/riscv/boot/vmlinux.bin
>   truncate: Invalid number: 'arch/riscv/boot/vmlinux.bin'
>   make[2]: *** [drivers/firmware/efi/libstub/Makefile.zboot:13: arch/riscv/boot/vmlinux.bin] Error 1
>   make[2]: *** Deleting file 'arch/riscv/boot/vmlinux.bin'
>   make[1]: *** [arch/riscv/Makefile:167: vmlinuz.efi] Error 2
>   make[1]: *** Waiting for unfinished jobs....
>     Kernel: arch/riscv/boot/Image is ready
>     GZIP    arch/riscv/boot/Image.gz
>     AS      arch/riscv/boot/loader.o
>     AS      arch/riscv/boot/loader.o
>     Kernel: arch/riscv/boot/loader is ready
>     OBJCOPY arch/riscv/boot/loader.bin
>     Kernel: arch/riscv/boot/loader.bin is ready
>     Kernel: arch/riscv/boot/Image.gz is ready
>   make: *** [Makefile:234: __sub-make] Error 2
>
> Image.gz, loader, vmlinuz.efi depend on Image. loader.bin depends
> on loader. Such dependencies are not specified in arch/riscv/Makefile.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> Changes in v2:
>   - Fix commit log
>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

>  arch/riscv/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 5cbe596345c1..1d6ed27e0a2a 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -163,6 +163,8 @@ BOOT_TARGETS := Image Image.gz loader loader.bin xipImage vmlinuz.efi
>
>  all:   $(notdir $(KBUILD_IMAGE))
>
> +loader.bin: loader
> +Image.gz loader vmlinuz.efi: Image
>  $(BOOT_TARGETS): vmlinux
>         $(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
>         @$(kecho) '  Kernel: $(boot)/$@ is ready'
> --
> 2.40.1
>