linux-kernel - Re: [PATCH RFC v3 05/21] ACPI: Rename ACPI_HOTPLUG

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Date:   Thu, 14 Dec 2023 17:41:07 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
CC:     <linux-pm@...r.kernel.org>, <loongarch@...ts.linux.dev>,
        <linux-acpi@...r.kernel.org>, <linux-arch@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-riscv@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
        <x86@...nel.org>, <acpica-devel@...ts.linuxfoundation.org>,
        <linux-csky@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-ia64@...r.kernel.org>, <linux-parisc@...r.kernel.org>,
        Salil Mehta <salil.mehta@...wei.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        <jianyong.wu@....com>, <justin.he@....com>,
        James Morse <james.morse@....com>
Subject: Re: [PATCH RFC v3 05/21] ACPI: Rename ACPI_HOTPLUG_CPU to include
 'present'

On Wed, 13 Dec 2023 12:49:37 +0000
Russell King (Oracle) <rmk+kernel@...linux.org.uk> wrote:

> From: James Morse <james.morse@....com>
> 
> The code behind ACPI_HOTPLUG_CPU allows a not-present CPU to become
> present. This isn't the only use of HOTPLUG_CPU. On arm64 and riscv
> CPUs can be taken offline as a power saving measure.
> 
> On arm64 an offline CPU may be disabled by firmware, preventing it from
> being brought back online, but it remains present throughout.
> 
> Adding code to prevent user-space trying to online these disabled CPUs
> needs some additional terminology.
> 
> Rename the Kconfig symbol CONFIG_ACPI_HOTPLUG_PRESENT_CPU to reflect
> that it makes possible CPUs present.
> 
> HOTPLUG_CPU is untouched as this is only about the ACPI mechanism.
> 
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Miguel Luis <miguel.luis@...cle.com>
> Tested-by: Vishnu Pajjuri <vishnu@...amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu@....com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
Formatting nitpick inline. Either way FWIW:
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 4db54e928b36..36071bc11acd 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h

>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
>  int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
> @@ -629,7 +629,7 @@ static inline u32 acpi_osc_ctx_get_cxl_control(struct acpi_osc_context *context)
>  #define ACPI_GSB_ACCESS_ATTRIB_RAW_PROCESS	0x0000000F
>  
>  /* Enable _OST when all relevant hotplug operations are enabled */
> -#if defined(CONFIG_ACPI_HOTPLUG_CPU) &&			\
> +#if defined(CONFIG_ACPI_HOTPLUG_PRESENT_CPU) &&			\

Trivial but I think there is a tab to many before that \

>  	defined(CONFIG_ACPI_HOTPLUG_MEMORY) &&		\
>  	defined(CONFIG_ACPI_CONTAINER)
>  #define ACPI_HOTPLUG_OST