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Date:   Tue, 06 Jun 2023 09:35:27 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Zhangjin Wu" <falcon@tinylab.org>, "Willy Tarreau" <w@1wt.eu>
Cc:     linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= <thomas@t-8ch.de>
Subject: Re: [PATCH v3 1/3] tools/nolibc: fix up #error compile failures with -ENOSYS
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On Sat, Jun 3, 2023, at 11:01, Zhangjin Wu wrote:
>
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Link: 
> https://lore.kernel.org/linux-riscv/5e7d2adf-e96f-41ca-a4c6-5c87a25d4c9c@app.fastmail.com/
> Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
> ---
>  tools/include/nolibc/sys.h | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
> index 856249a11890..78c86f124335 100644
> --- a/tools/include/nolibc/sys.h
> +++ b/tools/include/nolibc/sys.h
> @@ -124,7 +124,7 @@ int sys_chmod(const char *path, mode_t mode)
>  #elif defined(__NR_chmod)
>  	return my_syscall2(__NR_chmod, path, mode);
>  #else
> -#error Neither __NR_fchmodat nor __NR_chmod defined, cannot implement 
> sys_chmod()
> +	return -ENOSYS;
>  #endif
>  }

I think the most logical would be to have each syscall (chmod,
fchmodat, ...) have its own function that returns -ENOSYS if
that is not defined, and have the logic that decides which one
to use as a separate function.

This patch is a step in that direction though, so I think that's
totally fine.

     Arnd