linux-kernel - Re: [PATCH v3 2/3] kbuild: remove PROVIDE() for kallsyms symbols

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Message-ID: <20240613-monumental-basilisk-of-temperance-7dda6e@lindesnes>
Date: Thu, 13 Jun 2024 05:57:00 +0200
From: Nicolas Schier <nicolas@...sle.eu>
To: Masahiro Yamada <masahiroy@...nel.org>
Cc: linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
	Ard Biesheuvel <ardb@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	Nathan Chancellor <nathan@...nel.org>, linux-arch@...r.kernel.org
Subject: Re: [PATCH v3 2/3] kbuild: remove PROVIDE() for kallsyms symbols

On Mon, Jun 10, 2024 at 08:25:17PM +0900, Masahiro Yamada wrote:
> This reimplements commit 951bcae6c5a0 ("kallsyms: Avoid weak references
> for kallsyms symbols") because I am not a big fan of PROVIDE().
> 
> As an alternative solution, this commit prepends one more kallsyms step.
> 
>     KSYMS   .tmp_vmlinux.kallsyms0.S          # added
>     AS      .tmp_vmlinux.kallsyms0.o          # added
>     LD      .tmp_vmlinux.btf
>     BTF     .btf.vmlinux.bin.o
>     LD      .tmp_vmlinux.kallsyms1
>     NM      .tmp_vmlinux.kallsyms1.syms
>     KSYMS   .tmp_vmlinux.kallsyms1.S
>     AS      .tmp_vmlinux.kallsyms1.o
>     LD      .tmp_vmlinux.kallsyms2
>     NM      .tmp_vmlinux.kallsyms2.syms
>     KSYMS   .tmp_vmlinux.kallsyms2.S
>     AS      .tmp_vmlinux.kallsyms2.o
>     LD      vmlinux
> 
> Step 0 takes /dev/null as input, and generates .tmp_vmlinux.kallsyms0.o,
> which has a valid kallsyms format with the empty symbol list, and can be
> linked to vmlinux. Since it is really small, the added compile-time cost
> is negligible.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> Acked-by: Ard Biesheuvel <ardb@...nel.org>
> ---

Reviewed-by: Nicolas Schier <nicolas@...sle.eu>