Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220712075255.1345991-1-chenhuacai@loongson.cn>
 <20220712075255.1345991-3-chenhuacai@loongson.cn> <CAMuHMdUazqHLbc80vpZ+Msg9A3j5aPJ3fx+CdCG3kuWDSf8WSw@mail.gmail.com>
 <CAAhV-H775jXMbcR9j=oLBuHo1PfFziZSUQWttJAEw20sUt+GAA@mail.gmail.com> <CAMuHMdUHbepd974u5iox3BcOyo_Q2ZgT-znruk+WCt+HMQ_Lgw@mail.gmail.com>
In-Reply-To: <CAMuHMdUHbepd974u5iox3BcOyo_Q2ZgT-znruk+WCt+HMQ_Lgw@mail.gmail.com>
From:   Huacai Chen <chenhuacai@gmail.com>
Date:   Tue, 12 Jul 2022 17:08:42 +0800
Message-ID: <CAAhV-H78Fi0aE-h5MOgRa5L+Jt7D0wG0nLcYzx45jVney8T1BQ@mail.gmail.com>
Subject: Re: [PATCH 3/6] M68K: cpuinfo: Fix a warning for CONFIG_CPUMASK_OFFSTACK
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Michal Simek <monstr@monstr.eu>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, Jeff Dike <jdike@addtoit.com>,
        Richard Weinberger <richard@nod.at>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        loongarch@lists.linux.dev, Linux-Arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Linux-sh list <linux-sh@vger.kernel.org>,
        linux-um <linux-um@lists.infradead.org>,
        stable <stable@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi, Geert,

On Tue, Jul 12, 2022 at 5:01 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Huacai,
>
> On Tue, Jul 12, 2022 at 10:53 AM Huacai Chen <chenhuacai@gmail.com> wrote:
> > On Tue, Jul 12, 2022 at 4:33 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Tue, Jul 12, 2022 at 9:53 AM Huacai Chen <chenhuacai@loongson.cn> wrote:
> > > > When CONFIG_CPUMASK_OFFSTACK and CONFIG_DEBUG_PER_CPU_MAPS is selected,
> > >
> > > DEBUG_PER_CPU_MAPS depends on SMP, which is not supported on m68k,
> > > and thus cannot be enabled.
> > This patch is derived from MIPS and LoongArch, I search all
> > architectures and change those that look the same as MIPS and
> > LoongArch.
> > And the warning message below is also a copy-paste from LoongArch, sorry.
> >
> > Since M68K doesn't support SMP, then this patch seems to make no
> > difference, but does it make sense to keep consistency across all
> > architectures?
>
> Yes, having consistency is good.  But that should be mentioned in the
> patch description, instead of a scary warning CCed to stable ;-)
>
> BTW, you probably want to update the other copy of c_start() in
> arch/m68k/kernel/setup_mm.c, too.
For no-SMP architectures, it seems c_start() in
arch/m68k/kernel/setup_mm.c is more reasonable (just use 1, neither
NR_CPUS, nor nr_cpu_ids)?

Huacai
>
> Thanks!
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds