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

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 06/15/2010 03:49 AM, Mukesh Rathor wrote:
> On Mon, 14 Jun 2010 10:37:30 +0100
> Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>
>   
>> On 06/10/2010 03:13 AM, Mukesh Rathor wrote:
>>     
>>> Well, BUG_ON is only triggered if booting more than 32 VCPUs on a
>>> *very old* xen (pre xen 3.1.0). 
>>>
>>> Looking at code closely, we could just set setup_max_cpus to 32 some
>>> where in xen function, perhaps even in xen_vcpu_setup(). That way
>>> later in smp_init() it would just be ok. 
>>>   
>>>       
>> Yes.
>>
>>     
>>> One thing tho, the per cpus areas are already setup at that point,
>>> so that would need to be cleaned. BTW, I don't understand why 
>>> have_vcpu_info_placement is set to 0 in xen_guest_init()? 
>>>   
>>>       
>> xen_guest_init is used by the pvhvm path, and hvm domains don't have a
>> notion of vcpu info placement.
>>
>>     
>>> What minimum version of xen is required to run pvops kernel?
>>>   
>>>       
>> In theory it should be back-compatible for all Xen 3, but in practice
>> it tweaks lots of bugs in older Xens (particularly 32-on-64).  I
>> don't know that anyone has definitively established an earliest
>> version.  I implemented vcpu info placement for use in pvops kernels,
>> but it was never my intention that it be an absolute requirement.
>>
>>     J
>>     
> Ok, attached  patch without BUG_ON. Please feel free to modify
> to your liking also.
>   

It looks like you smashed all the tabs into spaces so its hard to see
what you've changed in the diff.  I'll fix it up and give it a look-over.

    J

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