Subject: Re: [RFC PATCH] MIPS: SMP-CPS: fix build error when HOTPLUG_CPU not
 set
To:     Randy Dunlap <rdunlap@infradead.org>, linux-kernel@vger.kernel.org
Cc:     Dengcheng Zhu <dzhu@wavecomp.com>,
        Paul Burton <paulburton@kernel.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org
References: <20230217063858.28311-1-rdunlap@infradead.org>
From:   Sergei Shtylyov <sergei.shtylyov@gmail.com>
Message-ID: <5e36b62c-9326-dc8b-3d7e-dfa79b75472b@gmail.com>
Date:   Fri, 17 Feb 2023 11:43:03 +0300
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On 2/17/23 9:38 AM, Randy Dunlap wrote:

> When MIPS_CPS=y, MIPS_CPS_PM is not set, HOTPLUG_CPU is not set, and
> KEXEC=y, cps_shutdown_this_cpu() attempts to call cps_pm_enter_state(),
> which is not built when MIPS_CPS_PM is not set.
> Conditionally execute the else branch based on CONFIG_HOTPLUG_CPU
> to remove the build error.
> This build failure is from a randconfig file.
> 
> mips-linux-ld: arch/mips/kernel/smp-cps.o: in function `$L162':
> smp-cps.c:(.text.cps_kexec_nonboot_cpu+0x31c): undefined reference to `cps_pm_enter_state'
> 
> Fixes: 1447864bee4c ("MIPS: kexec: CPS systems to halt nonboot CPUs")
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> Cc: Dengcheng Zhu <dzhu@wavecomp.com>
> Cc: Paul Burton <paulburton@kernel.org>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: linux-mips@vger.kernel.org
> ---
>  arch/mips/kernel/smp-cps.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff -- a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
> --- a/arch/mips/kernel/smp-cps.c
> +++ b/arch/mips/kernel/smp-cps.c
> @@ -424,9 +424,11 @@ static void cps_shutdown_this_cpu(enum c
>  			wmb();
>  		}
>  	} else {
> +#ifdef CONFIG_HOTPLUG_CPU

   Perhaps, instead of #ifdef'ery, ude the following:

	} else if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {

>  		pr_debug("Gating power to core %d\n", core);
>  		/* Power down the core */
>  		cps_pm_enter_state(CPS_PM_POWER_GATED);
> +#endif /* CONFIG_HOTPLUG_CPU */
>  	}
>  }
>  

MBR, Sergey