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From:   Huacai Chen <chenhuacai@kernel.org>
Date:   Wed, 10 Aug 2022 23:38:13 +0800
Message-ID: <CAAhV-H7DbvjEcms9Y81t_=WyDnKu5vuB4x7g7vU3f9CUhZykHQ@mail.gmail.com>
Subject: Re: [PATCH] LoongArch: Fix the !CONFIG_SMP build for irqchip drivers
To:     Marc Zyngier <maz@kernel.org>
Cc:     Huacai Chen <chenhuacai@loongson.cn>,
        Thomas Gleixner <tglx@linutronix.de>,
        loongarch@lists.linux.dev, Xuefeng Li <lixuefeng@loongson.cn>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        LKML <linux-kernel@vger.kernel.org>
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Hi, Marc,

On Wed, Aug 10, 2022 at 7:01 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2022-08-10 11:31, Huacai Chen wrote:
> > 1, Guard get_ipi_irq() in CONFIG_SMP;
> > 2, Define cpu_logical_map() for the EIOINTC driver;
> > 3, Make eiointc_set_irq_affinity() return early for !CONFIG_SMP.
> >
> > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
>
> Frankly, the real question is why do you even bother? As far as
> I can tell, LoongArch has no UP system.
>
> arm64 crossed that bridge a long time ago, and we never looked
> back, because these systems hardly exist.
>
> I'd rather you simply have a CONFIG_SMP always set to 'y', and
> be done with it forever.
LoongArch also has low-end processors (even LoongArch64). Though we
haven't translate all documents at
https://loongson.github.io/LoongArch-Documentation/ in time, there are
currently 4 LoongArch64 processors: Loongson-2K500 (single-core),
Loongon-2K1000 (dual-core), Loongson-3A5000 (quad-core) and
Loongson-3C5000 (16-core). So we indeed need a UP configuration.
Thanks.

Huacai
>
>          M.
> --
> Jazz is not dead. It just smells funny...