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Date: Tue, 07 Apr 2015 12:34:46 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] target-i386: clear bsp bit when designating bsp
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To: =?windows-1252?Q?Andreas_F=E4rber?= <afaerber@suse.de>, Nadav Amit <namit@cs.technion.ac.il>, mst@redhat.com, qemu-devel@nongnu.org
Cc: nadav.amit@gmail.com, Eduardo Habkost <ehabkost@redhat.com>, rth@twiddle.net



On 07/04/2015 12:15, Andreas F=E4rber wrote:
>>> >> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>>> >> index b2d1c95..03b33cf 100644
>>> >> --- a/target-i386/cpu.c
>>> >> +++ b/target-i386/cpu.c
>>> >> @@ -2714,9 +2714,7 @@ static void x86_cpu_reset(CPUState *s)
>>> >> =20
>>> >>  #if !defined(CONFIG_USER_ONLY)
>>> >>      /* We hard-wire the BSP to the first CPU. */
>>> >> -    if (s->cpu_index =3D=3D 0) {
>>> >> -        apic_designate_bsp(cpu->apic_state);
>>> >> -    }
>>> >> +    apic_designate_bsp(cpu->apic_state, s->cpu_index =3D=3D 0);
>>> >> =20
>>> >>      s->halted =3D !cpu_is_bsp(cpu);
>>> >> =20
>>> >>
>> >=20
>> > Thanks, applied locally.
> I don't understand why this is necessary: The cpu_index doesn't change,
> therefore the BSP designation won't change either.

It can change at runtime, though, if you're using the KVM in-kernel LAPIC.

Paolo

 Is this a hot-unplug
> preparation? Or is a KVM-specific call missing here? Either way, the
> commit message could use some clarification.