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Date:   Sun, 11 Sep 2022 17:26:18 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     linux-toolchains@vger.kernel.org,
        Indu Bhagat <indu.bhagat@oracle.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-kernel@vger.kernel.org, "Jose E. Marchesi" <jemarch@gnu.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Mark Rutland <mark.rutland@arm.com>,
        Will Deacon <will@kernel.org>, x86@kernel.org,
        linux-arm-kernel@lists.infradead.org,
        live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Chen Zhongjin <chenzhongjin@huawei.com>,
        Sathvika Vasireddy <sv@linux.ibm.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Mark Brown <broonie@kernel.org>
Subject: Re: [RFC] Objtool toolchain proposal:
 -fannotate-{jump-table,noreturn}
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References: <20220909180704.jwwed4zhwvin7uyi@treble>
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On Fri, Sep 09, 2022 at 11:07:04AM -0700, Josh Poimboeuf wrote:
> Alternatives
> ------------
> 
> Another idea which has been floated in the past is for objtool to read
> DWARF (or .eh_frame) to help it figure out the control flow.  That
> hasn't been tried yet, but would be considerably more difficult and
> fragile IMO.

I though Ard played around with that a bit on ARM64. And yes, given that
most toolchains consider DWARF itself best-effort, I'm not holding my
breath there.

On top of that, building a kernel with DWARFs on is just so much
slower..