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Message-ID: <c185e8a668e9b879af139ffa8d5104e643b3f66a.camel@infradead.org>
Subject: Re: [patch 00/37] cpu/hotplug, x86: Reworked parallel CPU bringup
From:   David Woodhouse <dwmw2@infradead.org>
To:     Thomas Gleixner <tglx@linutronix.de>,
        Paul Menzel <pmenzel@molgen.mpg.de>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        Andrew Cooper <andrew.cooper3@citrix.com>,
        Brian Gerst <brgerst@gmail.com>,
        Arjan van de Veen <arjan@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Paul McKenney <paulmck@kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Piotr Gorski <lucjan.lucjanov@gmail.com>,
        Usama Arif <usama.arif@bytedance.com>,
        =?ISO-8859-1?Q?J=FCrgen_Gro=DF?= <jgross@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        xen-devel@lists.xenproject.org,
        Russell King <linux@armlinux.org.uk>,
        Arnd Bergmann <arnd@arndb.de>,
        linux-arm-kernel@lists.infradead.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
        linux-csky@vger.kernel.org,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org,
        "James E. J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>, linux-parisc@vger.kernel.org,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        linux-riscv@lists.infradead.org,
        Mark Rutland <mark.rutland@arm.com>,
        Sabin Rapan <sabrapan@amazon.com>
Date:   Wed, 19 Apr 2023 14:32:54 +0100
In-Reply-To: <877cu83v45.ffs@tglx>
References: <20230414225551.858160935@linutronix.de>
         <8247ce4d-15b7-03b2-0c9b-74f8cd6cad50@molgen.mpg.de> <87wn2a4la5.ffs@tglx>
         <bd5a6a93-def1-9248-2258-c3d3b40071ef@molgen.mpg.de> <87ttxd4qxz.ffs@tglx>
         <87r0sh4m7a.ffs@tglx> <8592a301-9933-1cad-bd61-8d97e7c7493b@molgen.mpg.de>
         <87a5z443g2.ffs@tglx> <877cu83v45.ffs@tglx>
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On Wed, 2023-04-19 at 14:38 +0200, Thomas Gleixner wrote:
>=20
> I'm leaning towards disabling the CPUID lead 0x01 based discovery and be
> done with it.

Makes sense. The large machines where users really want the parallel
startup all ought to have X2APIC and hence CPUID 0x0b.


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