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Date: Tue, 13 May 2014 12:53:04 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] [PATCH 0/4] Support more than 255 cpus
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To: "Li, Zhen-Hua" <zhen-hual@hp.com>, qemu-devel@nongnu.org, Igor Mammedov <imammedo@redhat.com>, Eduardo Habkost <ehabkost@redhat.com>

On 2014-05-13 09:09, Li, Zhen-Hua wrote:
> From: "Li, ZhenHua" <zhen-hual@hp.com>
> 
> These series patches are trying to make Qemu support more than 255 CPUs. 
> The max cpu number changed to 4096.
> 
>  Support more than 255 cpus: ACPI and APIC defines
>  Support more than 255 cpus: max_cpus to 4096
>  Support more than 255 cpus: max cpumask bit to 4096
>  Support more than 255 cpus: runtime chec
> 
>  include/hw/acpi/cpu_hotplug_defs.h | 4 ++--
>  include/hw/i386/apic_internal.h    | 2 +-
>  include/hw/i386/pc.h | 2 +-
>  include/sysemu/sysemu.h | 2 +-
>  hw/i386/acpi-build.c | 8 ++++----

Don't we need x2APIC support to provide >255 CPUs? Where so you enforce
this, i.e. keep the restriction to 255 CPUs when we are not in KVM mode
with in-kernel APIC (the emulate APIC lacks x2APIC mode, unfortunately)?
But, wait, KVM only supports up to 255 VCPUs. So what are you targeting at?

Jan

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