From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [PATCHEs]: support more than 32 VCPUs in guests
Date: Wed, 09 Jun 2010 17:49:52 -0700
Message-ID: <4C1036B0.4060905@goop.org>
References: <20100609160920.1445fbbe@mantra.us.oracle.com>	<4C102742.3010108@goop.org>
	<20100609170825.06a67ff9@mantra.us.oracle.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xensource.com>
In-Reply-To: <20100609170825.06a67ff9@mantra.us.oracle.com>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Mukesh Rathor <mukesh.rathor@oracle.com>
Cc: "Xen-devel@lists.xensource.com" <Xen-devel@lists.xensource.com>
List-Id: xen-devel@lists.xenproject.org

On 06/09/2010 05:08 PM, Mukesh Rathor wrote:
>> Why BUG_ON if the number of cpus is too high?  Why not just ignore the
>> excess ones?
>>     
> Yeah, that was my first thought also... but then i realized i couldn't
> just ignore the excess cpus in that function, but would need to go back
> and fixup all the cpu_present, cpu_online, etc maps (and any assoc data
> structs, if any), and it just didn't seem worth it in the 2.6.18* 
> kernels at least. Would have been easier to do if the vcpu setup 
> function returned a value instead of being void. 
>   

Yes, but if have_vcpu_info_placement ends up being false (which is
tested before any other cpus are brought up) then you can simply fail to
online the ones above the limit.

BUG_ON is way too brutal.  You need to fail more softly.

    J