[Xen-devel] Re: [PATCHEs]: support more than 32 VCPUs in guests

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

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

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