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From:   Andreas Schwab <schwab@linux-m68k.org>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Nathan Chancellor <nathan@kernel.org>, linux-arch@vger.kernel.org,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Thorsten Leemhuis <regressions@leemhuis.info>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        linux-riscv@lists.infradead.org, Dennis Gilmore <dennis@ausil.us>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Arnd Bergmann <arnd@arndb.de>,
        Jisheng Zhang <jszhang@kernel.org>,
        Nicolas Schier <nicolas@fjasle.eu>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>, llvm@lists.linux.dev
Subject: Re: [PATCH v2] arch: fix broken BuildID for arm64 and riscv
References: <20221226184537.744960-1-masahiroy@kernel.org>
        <Y7Jal56f6UBh1abE@dev-arch.thelio-3990X>
        <CAK7LNAQ-MWhbiTX=phy3uzmNn+6ABZmi49D6d1n1-k-jxcQzgA@mail.gmail.com>
Date:   Thu, 05 Jan 2023 10:21:03 +0100
In-Reply-To: <CAK7LNAQ-MWhbiTX=phy3uzmNn+6ABZmi49D6d1n1-k-jxcQzgA@mail.gmail.com>
        (Masahiro Yamada's message of "Thu, 5 Jan 2023 12:22:50 +0900")
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On Jan 05 2023, Masahiro Yamada wrote:

> I do not understand why 99cb0d917ffa affected this.
>
>
> I submitted a fix to shoot the error message "discarded section .exit.text"
>
> https://lore.kernel.org/all/20230105031306.1455409-1-masahiroy@kernel.org/T/#u
>
> I do not understand the binutils commit either,
> but it might have made something good
> because EXIT_TEXT appears twice, in .exit.text, and /DISCARD/.

I think the issue is that the introdution of a second /DISCARD/
directive early in script changes the order of evaluation of the other
/DISCARD/ directive when binutils < 2.36 is used, so that the missing
RUNTIME_DISCARD_EXIT started to become relevant.  As long as /DISCARD/
only appears last, the effect of EXIT_TEXT inside it is always
overridden by its occurence in the .exit.exit output section directive.
When another /DISCARD/ occurs early (and binutils < 2.36 is used) the
effect of EXIT_TEXT inside the second /DISCARD/ (when merged with the
first) overrides its occurence in the .exit.text directive.  The
binutils commit changed that because the new /DISCARD/ directive no
longer affects the order of evaluation of the rest of the directives.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."