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From:   Huacai Chen <chenhuacai@kernel.org>
Date:   Thu, 20 Jul 2023 09:55:51 +0800
Message-ID: <CAAhV-H7K2qM35GuGV+B2p=N_f30i98KazvwVNCuvvG9fYfrghw@mail.gmail.com>
Subject: Re: [PATCH 0/3] MIPS: Fix build issues from the introduction of `need-compiler'
To:     "Maciej W. Rozycki" <macro@orcam.me.uk>
Cc:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Jan-Benedict Glaw <jbglaw@lug-owl.de>,
        Guillaume Tucker <guillaume.tucker@collabora.com>,
        Huacai Chen <chenhuacai@loongson.cn>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
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Hi, Maciej,

On Wed, Jul 19, 2023 at 11:39=E2=80=AFPM Maciej W. Rozycki <macro@orcam.me.=
uk> wrote:
>
> On Tue, 18 Jul 2023, Huacai Chen wrote:
>
> > Even if patch-2 resolves the problem, I don't think patch-3 is
> > necessary because the original patch makes code simpler and more
> > compact.
>
>  Please don't top-post on a public mailing list.
>
>  If you're referring to this part:
>
> +ifdef CONFIG_CPU_LOONGSON64
> +cflags-$(CONFIG_CPU_LOONGSON64)        +=3D -Wa,--trap
> +cflags-$(CONFIG_CC_IS_GCC) +=3D -march=3Dloongson3a
> +cflags-$(CONFIG_CC_IS_CLANG) +=3D -march=3Dmips64r2
> +endif
>
> then it can be done with a separate clean-up.  Otherwise it'll have been
> lost in the noise.
>
>  Firstly:
>
> cflags-$(CONFIG_CPU_LOONGSON64) +=3D -Wa,--trap
>
> doesn't have to be wrapped in `ifdef CONFIG_CPU_LOONGSON64'.
>
>  Secondly:
>
> cflags-$(CONFIG_CC_IS_GCC) +=3D -march=3Dloongson3a
> cflags-$(CONFIG_CC_IS_CLANG) +=3D -march=3Dmips64r2
>
> document compiler peculiarities.  Does Clang support, or intend to,
> `-march=3Dloongson3a'?  If so, what version can we expect this stuff in?
> GCC has had it since 4.6 or Y2010, which is pretty long ago.
GCC support loongson3a/mips64r2, Clang only support mips64r2. If we use
$(call cc-option,-march=3Dloongson3a,-march=3Dmips64r2)
both GCC and Clang can work and we don't need to care about the compiler.

Huacai

>
>  Last but not least there are formatting anomalies there, which may have
> to be dealt with in a separate change.
>
>   Maciej