linux-kernel - Re: [PATCH 2/4] tools/nolibc: avoid unused parameter warnings for ENOSYS fallbacks

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Date:   Sun, 17 Sep 2023 17:07:18 +0200
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Willy Tarreau <w@....eu>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 2/4] tools/nolibc: avoid unused parameter warnings for
 ENOSYS fallbacks

On 2023-09-17 11:48:27+0200, Willy Tarreau wrote:
> [..]
> > Maybe the macro-equivalent of this?
> > 
> > static inline int __nolibc_enosys(...)
> > {
> > 	return -ENOSYS;
> > }
> > 
> > The only-vararg function unfortunately needs C23 so we can't use it.
> >
> > It's clear to the users that this is about ENOSYS and we don't need a
> > bunch of new macros similar.
> 
> I like it, I didn't think about varargs, it's an excellent idea! Let's
> just do simpler, start with a first arg "syscall_num" that we may later
> reuse for debugging, and just mark this one unused:
> 
>   static inline int __nolibc_enosys(int syscall_num, ...)
>   {
> 	(void)syscall_num;
>   	return -ENOSYS;
>   }

But which syscall_num to use, as the point of __nolibc_enosys() would be
that no syscall number is available and the defines are missing.

For debugging we could add a string argument, though.