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Re: [Xen-devel] [PATCH v3 8/8] xen: arm: allocate more than one bank for 1:1 domain 0 if needed

On 06/30/2014 05:14 PM, Ian Campbell wrote:
> On Mon, 2014-06-30 at 17:10 +0100, Julien Grall wrote:
>> Hi Ian,
>> On 06/30/2014 04:58 PM, Ian Campbell wrote:
>>> On Fri, 2014-06-27 at 14:09 +0100, Ian Campbell wrote:
>>>> On Fri, 2014-06-27 at 14:04 +0100, Julien Grall wrote:
>>>>> On 27/06/14 14:01, Ian Campbell wrote:
>>>>>>> Futhermore, it looks like we always allocate memory from the top of this
>>>>>>> zone. Is it normal?
>>>>>> Normal behaviour is to allocate from as high as possible so I'm not
>>>>>> surprised that applies with a zone as well.
>>>>> For DOM0 bank allocation, shouldn't we try to allocate as lower as 
>>>>> possible? If not, we may not be able to create a second bank for dom0.
>>>> The loop over bits is supposed to help there, but it's not as effective
>>>> with higher addresses I suppose.
>>>> We'd need a new flag fore the allocate. Which is doable I guess. I'll
>>>> give it a try.
>>> It's a bit tricky and involves messing with the guts of the page
>>> allocator, which I'd rather avoid...
>>> We do allow allocations to be merged onto the start of bank 0, which in
>>> the normal case is what I would expect to happen, although it isn't
>>> guaranteed. In that case we would try higher addresses and might find
>>> enough RAM there.
>>> I suppose I could relax the constraint a bit and allow new banks in
>>> front of bank zero if they were >= 128MB (say).
>> So, replacing the bank zero by the new bank, right? IIRC, some Linux
>> version are requiring the bank to be ordered.
> Inserting the new bank before, retaining the ordering.

Thanks, this plan sounds good!

Julien Grall

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