Re: [Xen-devel] [PATCH 1/1] xc_domain_restore: Allow QEMU to increase memory

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 04/15/15 07:56, Ian Campbell wrote:
> On Wed, 2015-04-15 at 12:27 +0100, Stefano Stabellini wrote:
>> On Wed, 15 Apr 2015, Hongyang Yang wrote:
>>> On 04/15/2015 06:09 PM, Ian Campbell wrote:
>>>> On Wed, 2015-04-15 at 10:46 +0100, Stefano Stabellini wrote:
>>>>> On Tue, 14 Apr 2015, Don Slutz wrote:
>>>>>> On 04/14/15 04:53, Wei Liu wrote:
>>>>>>> Is there a way to know how much more memory each option rom needs? If
>>>>>>> so, you can correctly account for the extra memory you need. This
>>>>>>> would
>>>>>>> be an ideal fix to this problem.
>>>>>>
>>>>>> I do not know of a way to get this info.  It can change based on the
>>>>>> QEMU version.
>>>>>
>>>>> Indeed it would be fragile to rely on a fixed size for each option rom,
>>>>> given that they come out of the QEMU tree and can change at any time.
>>>>
>>>> Only having dipped into this thread so far it seems to me we need some
>>>> way for qemu to communicate the result of its manipulations of maxmem
>>>> into the migration stream explicitly to be picked up by the other end.
>>>
>>> Totally agreed.
>>
>> Xen knows exactly the maxmem setting for the domain, I don't think we
>> need one more notification from QEMU?
>> Libxl/Xen could just write the maxmem value to the migration stream.
> 
> If that is all which is needed and not the delta between the notional
> maxmem which the guest was configured with and what we actually gave it
> due to things such as option ROMs, then sure.
> 

This is what v2 of this patch does.

   -Don Slutz

> Ian.
> 

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