From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: KVM_MAX_VCPUS
Date: Sun, 14 Oct 2012 11:08:26 +0200
Message-ID: <20121014090825.GM16648@redhat.com>
References: <5079EB5B.8080102@hp.com>
 <507A242D.9070708@gmail.com>
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Cc: Chegu Vinod <chegu_vinod@hp.com>, KVM <kvm@vger.kernel.org>
To: Sasha Levin <levinsasha928@gmail.com>
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On Sat, Oct 13, 2012 at 10:32:13PM -0400, Sasha Levin wrote:
> On 10/13/2012 06:29 PM, Chegu Vinod wrote:
> > Hello,
> > 
> > Wanted to get a clarification about KVM_MAX_VCPUS(currently set to 254)
> >  in kvm_host.h file. The kvm_vcpu *vcpus array is sized based on KVM_MAX_VCPUS.
> > (i.e. a max of 254 elements in the array).
> >  
> > An 8bit APIC id should allow for 256 ID's. Reserving one for Broadcast should
> > leave 255 ID's.  Is there one more ID reserved for some other purpose ? (hence
> > leading to KVM_MAX_VCPUS being set to 254 and not 255).
> 
> Another ID goes to the IO-APIC.
> 
This is not really needed on KVM. We can enlarge KVM_MAX_VCPUS to 255.

--
			Gleb.