Re: [Xen-devel] [PATCH] Disallow setting maxmem to higher value than total physical memory size

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 01.09.10 at 17:10, Michal Novotny <minovotn@xxxxxxxxxx> wrote:
> On 09/01/2010 05:00 PM, Jan Beulich wrote:
>>>>> On 01.09.10 at 16:50, Michal Novotny<minovotn@xxxxxxxxxx>  wrote:
>>>>>          
>>> On 09/01/2010 04:26 PM, Jan Beulich wrote:
>>>      
>>>>>>> On 01.09.10 at 16:18, Michal Novotny<minovotn@xxxxxxxxxx>   wrote:
>>>>>>>
>>>>>>>              
>>>>> Oh, ok. It's not limited to dom0 nevertheless I don't see anything to be
>>>>>
>>>>>          
>>>> And how does this play together with physical memory hotplug?
>>>>
>>>> Jan
>>>>
>>>>
>>>>        
>>> Well, it's reading the physical memory size using the xc.physinfo() call
>>> so if this is handled correctly by hypervisor (since this  basically
>>> issues a hypercall) then it should be working fine.
>>>      
>> Meaning the tools would auto-adjust maxmem_kb' for Dom0 when
>> new memory got added? I can't see where that happens.
>>
>> Jan
>>
>>    
> It's all based on xc.physinfo() call which is basically a hypercall. If 
> there's a valid value coming from the hypervisor then it would be 
> working fine.
> 
> You can see the call is there always on this line of my patch:
> 
> + total_mem = int(xc.physinfo()['total_memory'])

But note that this line you add to recreate(), and I don't think this
will get executed a second time long after xend started.

> If this is handled correctly by hypervisor then we're good in user-space 
> as can be seen in tools/python/xen/lowlevel/xc/xc.c and 
> tools/libxl/libxl.c where call to tools/libxc/xc_misc.c:xc_physinfo() 
> resides.

Jan


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