linux-kernel - Re: [PATCH] init: keep boot_command

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Date:   Wed, 26 Jul 2023 19:02:55 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Nick Desaulniers" <ndesaulniers@...gle.com>,
        "Arnd Bergmann" <arnd@...nel.org>
Cc:     "Paul E. McKenney" <paulmck@...nel.org>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        "Kees Cook" <keescook@...omium.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Sami Tolvanen" <samitolvanen@...gle.com>,
        "Alexey Dobriyan" <adobriyan@...il.com>,
        "Masahiro Yamada" <masahiroy@...nel.org>,
        "Josh Poimboeuf" <jpoimboe@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] init: keep boot_command_line after init

On Wed, Jul 26, 2023, at 18:25, Nick Desaulniers wrote:
> On Wed, Jul 26, 2023 at 7:33 AM Arnd Bergmann <arnd@...nel.org> wrote:
>>
>> From: Arnd Bergmann <arnd@...db.de>
>>
>> The boot command line is not available after the init section gets discarded,
>> so adding a permanent reference to it causes a link time warning:
>>
>> WARNING: modpost: vmlinux: section mismatch in reference: cmdline_load_proc_show+0x2 (section: .text) -> boot_command_line (section: .init.data)
>
> cmdline_load_proc_show is probably inlined, but should it also be
> marked __init?  It's lone call site seems to be __init AFAICT.
>

No, that's not what it does: cmdline_load_proc_show() is called
when someone reads /proc/cmdline_load from userspace. It's only
the function that creates this procfs file that is __init, but the
call happens later.

      Arnd