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Date: Tue, 7 Apr 2015 16:26:04 +0300
From: "Denis V. Lunev" <den@openvz.org>
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Subject: Re: [Qemu-devel] target-i386: clear bsp bit when designating bsp
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To: Paolo Bonzini <pbonzini@redhat.com>, =?windows-1252?Q?Andreas_F=E4r?= =?windows-1252?Q?ber?= <afaerber@suse.de>, qemu-devel@nongnu.org
Cc: Eduardo Habkost <ehabkost@redhat.com>, mst@redhat.com, Nadav Amit <namit@cs.technion.ac.il>, Igor Mammedov <imammedo@redhat.com>, nadav.amit@gmail.com, rth@twiddle.net

On 07/04/15 16:18, Paolo Bonzini wrote:
>
>
> On 07/04/2015 13:57, Andreas Färber wrote:
>>>> If this is some issue with sync'ing state back and forth before QEMU and
>>>> KVM then the real issue has not been explained.
>> Hm, hw/intc/apic_common.c:apic_reset_common() has:
>>
>>      bsp = cpu_is_bsp(s->cpu);
>>      s->apicbase = APIC_DEFAULT_ADDRESS |
>>          (bsp ? MSR_IA32_APICBASE_BSP : 0) | MSR_IA32_APICBASE_ENABLE;
>>
>> What this is doing is really:
>>
>>      bsp = cpu_get_apic_base(s->cpu->apic_state) & MSR_IA32_APICBASE_BSP;
>>      s->apicbase = APIC_DEFAULT_ADDRESS |
>>          (bsp ? MSR_IA32_APICBASE_BSP : 0) | MSR_IA32_APICBASE_ENABLE;
>>
>> Unless I'm missing something, since we are in the APIC device's reset
>> function, this is effectively a twisted way of writing:
>>
>>      bsp = s->apicbase & MSR_IA32_APICBASE_BSP;
>>      s->apicbase = APIC_DEFAULT_ADDRESS |
>>          (bsp ? MSR_IA32_APICBASE_BSP : 0) | MSR_IA32_APICBASE_ENABLE;
>
> Yes, this is more readable.

just $0.02 :)

why don't
         bsp = s->apicbase & MSR_IA32_APICBASE_BSP;
         s->apicbase =
		APIC_DEFAULT_ADDRESS | bsp | MSR_IA32_APICBASE_ENABLE;
in this case. This looks the same from the textual point of view.

Den