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

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 07/16/2010 06:06 PM, Mukesh Rathor wrote:
> On Tue, 15 Jun 2010 11:45:43 -0700
> Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
>
>   
>> On Tue, 15 Jun 2010 09:30:35 +0100
>> Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>>
>>     
>>> 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
>>>       
>> Sorry, I've tabs turned off because patches I submit to other product
>> I work on must be tab free.  Anyways, re attached a new one with tabs.
>>
>> thanks again,
>> Mukesh
>>
>> Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
>>     
> Hi Jeremy,
>
> Just curious, did this patch ever make it?
>   

Probably not.  Looks like I forgot to tag it as "mail containing patch"
so it fell through the cracks.
   
    J

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