linux-kernel - Re: [PATCH v3 6/7] kbuild: use obj-y instead extra-y for objects placed at the head

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Message-ID: <2008526a-e0ca-7e67-cff6-b540d62e58c7@kernel.org>
Date:   Wed, 26 Oct 2022 10:35:45 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Michael Matz <matz@...e.de>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Martin Liška <mliska@...e.cz>,
        Borislav Petkov <bpetkov@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: Re: [PATCH v3 6/7] kbuild: use obj-y instead extra-y for objects
 placed at the head

On 25. 10. 22, 14:26, Michael Matz wrote:
>> Ideas, comments? I'll send the attachment as a PATCH later (if there are
>> no better suggestions).
> 
> This will work.  An alternative way would be to explicitly name the input
> file in the section commands, without renaming the section:
> 
> @@ -126,6 +126,7 @@ SECTIONS
>                  _text = .;
>                  _stext = .;
>                  /* bootstrapping code */
> +               KEEP(vmlinux.a:head64.o(.head.text))
>                  HEAD_TEXT
>                  TEXT_TEXT
> 
> But I guess not all arch's name their must-be-first file head64.o (or even
> have such requirement), so that's probably still arch-dependend and hence
> not inherently better than your way.

The downside of this is that it doesn't make sure the function 
(startup_64()) is the first one. When someone sticks something before 
it, it breaks again. But leaving the decision up to the x86 maintainers ;).

Re. other archs, I have absolutely no idea (haven't looked into that at 
all).

thanks,
-- 
js