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

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Message-ID: <871qpjrwfl.ffs@tglx>
Date:   Thu, 01 Dec 2022 16:11:10 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Borislav Petkov <bp@...en8.de>,
        Mateusz Jończyk <mat.jonczyk@...pl>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Ingo Molnar <mingo@...hat.com>,
        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

On Wed, Oct 26 2022 at 20:38, Borislav Petkov wrote:
> On Sun, Sep 11, 2022 at 10:47:02AM +0200, Mateusz Jończyk wrote:
>> 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.
>
> Can we do that without any detriment to older systems which don't have
> x2APIC?

Can we please adjust to reality and do:

    X86_X2APIC
    bool
    default y if X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)

There is zero reason for having a knob.

Thanks,

        tglx