From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: xl: expose max_cpu_id from `xl info`
Date: Wed, 14 Mar 2012 16:24:25 +0000
Message-ID: <4F60C639.1020307@citrix.com>
References: <4F5F7B49.9040001@citrix.com> <4F5F9CCF.9000400@oracle.com>
	<4F6076D1.3000804@citrix.com> <4F60BDBA.3040209@oracle.com>
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To: Zhigang Wang <zhigang.x.wang@oracle.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>
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<snip>
>>> Is this true: nr_cpus = max_cpu_id + 1 ?
>>>
>>> Zhigang
>>
>> if and only if all cpus are online.
>>
>> nr_cpus is set to nr_online_cpus() in the hypercall, while max_cpu_id
>> is set to nr_cpu_ids-1.
>>
>> nr_cpus is liable to change during runtime, while max_cpu_id is not.
>>
>> ~Andrew
>
> If this is the case, I think nr_cpus is a bit confusing. Can we make
> it always representing the number of physical cpus (from hypervisor's
> viewpoint, not dom0)?
>
> Zhigang
>
>

No.  The names here reflect the hypercall name parameters.  The
hypercall cant be changed because it is an ABI, and the "name : value"
pairs here cant be changed because of backward compatibility with the
previous toolstack.

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com