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From:   Thomas Gleixner <tglx@linutronix.de>
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To:     Borislav Petkov <bp@alien8.de>,
        Mateusz =?utf-8?Q?Jo=C5=84czyk?= <mat.jonczyk@o2.pl>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Yinghai Lu <yinghai@kernel.org>,
        Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH v2 01/10] x86/Kconfig: enable X86_X2APIC by default and
 improve help text
In-Reply-To: <Y1l+v3uG7tSUZfd0@zn.tnic>
References: <20220911084711.13694-1-mat.jonczyk@o2.pl>
 <20220911084711.13694-2-mat.jonczyk@o2.pl> <Y1l+v3uG7tSUZfd0@zn.tnic>
Date:   Thu, 01 Dec 2022 16:11:10 +0100
Message-ID: <871qpjrwfl.ffs@tglx>
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On Wed, Oct 26 2022 at 20:38, Borislav Petkov wrote:
> On Sun, Sep 11, 2022 at 10:47:02AM +0200, Mateusz Jo=C5=84czyk 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