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Message-ID: <218f068c-40b5-4f93-b26a-c300054be11e@sifive.com>
Date:   Tue, 21 Nov 2023 11:51:04 -0600
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Subject: Re: [PATCH v2] riscv: add dependency among Image(.gz), loader(.bin),
 and vmlinuz.efi
Content-Language: en-US
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Simon Glass <sjg@chromium.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv@lists.infradead.org
References: <20231119100024.2370992-1-masahiroy@kernel.org>
From:   Samuel Holland <samuel.holland@sifive.com>
In-Reply-To: <20231119100024.2370992-1-masahiroy@kernel.org>
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On 2023-11-19 4:00 AM, Masahiro Yamada 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
> 
>  arch/riscv/Makefile | 2 ++
>  1 file changed, 2 insertions(+)

Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>