linux-kernel - Re: [PATCH 0/2] Kconfig: -O3 enablement

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Message-ID: <CAKwvOd=Bmu40+_11GOBTeJBjToUf0LNG_RX0RiLcRLimUUkgcw@mail.gmail.com>
Date:   Tue, 21 Jun 2022 09:16:45 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Miko Larsson <mikoxyzzz@...il.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Sean Christopherson <seanjc@...gle.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Chris Down <chris@...isdown.name>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        John Ogness <john.ogness@...utronix.de>,
        Elliot Berman <quic_eberman@...cinc.com>,
        Oleksandr Natalenko <oleksandr@...hat.com>
Subject: Re: [PATCH 0/2] Kconfig: -O3 enablement

On Tue, Jun 21, 2022 at 6:35 AM Miko Larsson <mikoxyzzz@...il.com> wrote:
>
> Hi,
>
> This very small series allows -O3 to be used for all architectures. The
> first patch marks -O3 as experimental, with the reasoning being that it
> might expose unwanted regressions to users, and the second patch
> actually allows -O3 by removing the "depend on ARC" string.

I think we should just remove -O3 support from KCONFIG.

If someone wants to mess around with "experimental features," there's
nothing stopping you from doing:

$ make KCFLAGS=-O3

>
> The reasoning behind this series is to open up -O3 so that bugs related
> to it (both compiler-related and kernel-related) can be discovered by
> eyeballs wanting to improve the "-O3 experience," as that might be
> beneficial to both compilers and the kernel. This has been attempted
> before [1], but unfortunately nothing ever came of it.
>
> [1] https://lore.kernel.org/lkml/20191211104619.114557-1-oleksandr@redhat.com/
>
> Cc: linux-kbuild@...r.kernel.org
> Cc: x86@...nel.org
> Cc: Nathan Chancellor <nathan@...nel.org>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Nick Desaulniers <ndesaulniers@...gle.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> Cc: Sean Christopherson <seanjc@...gle.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@...nel.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Chris Down <chris@...isdown.name>
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Cc: John Ogness <john.ogness@...utronix.de>
> Cc: Elliot Berman <quic_eberman@...cinc.com>
> Cc: Oleksandr Natalenko <oleksandr@...hat.com>
>
> Miko Larsson (2):
>   Kconfig: Mark -O3 as experimental
>   Kconfig: Allow -O3 for all architectures
>
>  init/Kconfig | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> --
> 2.36.1
>


-- 
Thanks,
~Nick Desaulniers