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References: <20220426083259.526685-1-starzhangzsd@gmail.com> <alpine.DEB.2.21.2204270130210.9383@angie.orcam.me.uk>
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From:   Stephen Zhang <starzhangzsd@gmail.com>
Date:   Wed, 27 Apr 2022 09:57:33 +0800
Message-ID: <CANubcdWwHXqC4gUztNseoConYHp+G4nUSYFaO-Te3jFVqT=1sw@mail.gmail.com>
Subject: Re: [PATCH] arch/mips/kernel/traps: add CONFIG_MIPS_FP_SUPPORT when
 using handle_fpe
To:     "Maciej W. Rozycki" <macro@orcam.me.uk>
Cc:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        liam.howlett@oracle.com, ebiederm@xmission.com, dbueso@suse.de,
        alobakin@pm.me, f.fainelli@gmail.com,
        zhangshida <zhangshida@kylinos.cn>, linux-kernel@vger.kernel.org,
        linux-mips@vger.kernel.org
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Maciej W. Rozycki <macro@orcam.me.uk> =E4=BA=8E2022=E5=B9=B44=E6=9C=8827=E6=
=97=A5=E5=91=A8=E4=B8=89 08:40=E5=86=99=E9=81=93=EF=BC=9A
>
>  No need to conditionalise this either, because `cpu_has_fpu' is forced 0
> (in arch/mips/include/asm/cpu-features.h) if !CONFIG_MIPS_FP_SUPPORT.  So
> this code translates to:
>
>  if (0 && !0)
>   set_except_vector(15, handle_fpe);
>
> in the preprocessor if CONFIG_MIPS_FP_SUPPORT is unset and is optimised
> away.  Otherwise it should be written as:
>
>         if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT) && ...
>
> so as not to clutter C code with #ifdef, as per our coding style.
>
>   Maciej

Thanks for your comment. Do you mean  the following code:

 if (0 && !0)
    set_except_vector(15, handle_fpe);

will be optimised away if !CONFIG_MIPS_FP_SUPPORT?
But we did get =E2=80=9Cundefined reference to `handle_fpe=E2=80=9D  error =
when compiled with
!CONFIG_MIPS_FP_SUPPORT.