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Date:   Wed, 30 Aug 2023 19:31:19 +0100
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     James Morse <james.morse@arm.com>
Cc:     linux-pm@vger.kernel.org, loongarch@lists.linux.dev,
        kvmarm@lists.linux.dev, kvm@vger.kernel.org,
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        Marc Zyngier <maz@kernel.org>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
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        WANG Xuerui <kernel@xen0n.name>,
        Salil Mehta <salil.mehta@huawei.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>
Subject: Re: [RFC PATCH 02/32] ACPI: Move ACPI_HOTPLUG_CPU to be enabled per
 architecture
Message-ID: <ZO+K9+C+RgNeZ7Nq@shell.armlinux.org.uk>
References: <20230203135043.409192-1-james.morse@arm.com>
 <20230203135043.409192-3-james.morse@arm.com>
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Sender: Russell King (Oracle) <linux@armlinux.org.uk>
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On Fri, Feb 03, 2023 at 01:50:13PM +0000, James Morse wrote:
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -15,6 +15,7 @@ config IA64
>  	select ARCH_MIGHT_HAVE_PC_PARPORT
>  	select ARCH_MIGHT_HAVE_PC_SERIO
>  	select ACPI
> +	select ACPI_HOTPLUG_CPU if ACPI
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -5,6 +5,7 @@ config LOONGARCH
>  	select ACPI
>  	select ACPI_GENERIC_GSI if ACPI
>  	select ACPI_MCFG if ACPI
> +	select ACPI_HOTPLUG_CPU if ACPI
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -59,6 +59,7 @@ config X86
>  	#
>  	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
>  	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
> +	select ACPI_HOTPLUG_CPU			if ACPI
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -309,7 +309,6 @@ config ACPI_HOTPLUG_CPU
>  	bool
>  	depends on ACPI_PROCESSOR && HOTPLUG_CPU
>  	select ACPI_CONTAINER
> -	default y

When selecting the symbol, it's a good idea to ensure that its
dependencies are satisfied. So here, ACPI_HOTPLUG_CPU depends on
ACPI_PROCESSOR and HOTPLUG_CPU.

For x86, you're selecting ACPI_HOTPLUG_CPU if ACPI is enabled,
and ACPI can be freely enabled. HOTPLUG_CPU depends on SMP,
which is also a freely selectable option. Lastly,
ACPI_PROCESSOR depends on X86 || IA64 || ARM64 || LOONGARCH,
and is a user selectable, defaulting-y option if ACPI is
enabled.

So, shouldn't the x86 select be:

	select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU

?

I suspect similar issues exist for the other architecture Kconfig files
modified above.

This seems to also be in the latest rfc too, which is why I'm bringing
it up.

Thanks.

-- 
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