linux-kernel - RE: [PATCH v2 01/10] x86/Kconfig: enable X86_X2APIC by default and improve help text

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Message-ID: <MW5PR84MB18424DF86AE0D9B60994A38BAB339@MW5PR84MB1842.NAMPRD84.PROD.OUTLOOK.COM>
Date:   Thu, 27 Oct 2022 14:45:54 +0000
From:   "Elliott, Robert (Servers)" <elliott@....com>
To:     Mateusz Jończyk <mat.jonczyk@...pl>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Yinghai Lu <yinghai@...nel.org>,
        "Randy Dunlap" <rdunlap@...radead.org>
Subject: RE: [PATCH v2 01/10] x86/Kconfig: enable X86_X2APIC by default and
 improve help text

> As many current platforms (most modern Intel CPUs and QEMU) have x2APIC
> present, enable CONFIG_X86_X2APIC by default as it gives performance
> and functionality benefits. Additionally, if the BIOS has already
> switched APIC to x2APIC mode, but CONFIG_X86_X2APIC is disabled, the
> kernel will panic in arch/x86/kernel/apic/apic.c .
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> @@ -440,15 +440,27 @@ config X86_FEATURE_NAMES
>  	  If in doubt, say Y.
> 
>  config X86_X2APIC
> -	bool "Support x2apic"
> +	bool "x2APIC interrupt controller architecture support"
>  	depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP ||
> HYPERVISOR_GUEST)
> +	default y

Could this option be added to
	arch/x86/configs/x86_64_defconfig

so defconfig builds don't crash on current platforms?