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Date: Wed, 3 Mar 2010 18:00:22 +0200
From: Gleb Natapov <gleb@redhat.com>
Message-ID: <20100303160022.GG16909@redhat.com>
References: <cover.1267463833.git.jan.kiszka@siemens.com>
	<ca058ae38e22e417f9847e487cf657761ffbaab7.1267463833.git.jan.kiszka@siemens.com>
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Subject: [Qemu-devel] Re: [PATCH v4 03/10] x86: Extend validity of cpu_is_bsp
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To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org, qemu-devel@nongnu.org

On Mon, Mar 01, 2010 at 06:17:22PM +0100, Jan Kiszka wrote:
> As we hard-wire the BSP to CPU 0 anyway and cpuid_apic_id equals
> cpu_index, cpu_is_bsp can also be based on the latter directly. This
> will help an early user of it: KVM while initializing mp_state.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  hw/pc.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/pc.c b/hw/pc.c
> index b90a79e..58c32ea 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -767,7 +767,8 @@ static void pc_init_ne2k_isa(NICInfo *nd)
>  
>  int cpu_is_bsp(CPUState *env)
>  {
> -    return env->cpuid_apic_id == 0;
> +    /* We hard-wire the BSP to the first CPU. */
> +    return env->cpu_index == 0;
>  }
We should not assume that. The function was written like that
specifically so the code around it will not rely on this assumption.
Now you change that specifically to write code that will do incorrect
assumptions. I don't see the logic here.

>  
>  CPUState *pc_new_cpu(const char *cpu_model)
> -- 
> 1.6.0.2

--
			Gleb.