From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH v2 04/10] xen/arm: Store p2m type in each
 page of the guest
Date: Tue, 10 Dec 2013 13:50:15 +0000
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To: Ian Campbell <Ian.Campbell@citrix.com>
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On 12/10/2013 09:37 AM, Ian Campbell wrote:
> On Tue, 2013-12-10 at 01:55 +0000, Julien Grall wrote:
>> On 12/09/2013 04:53 PM, Ian Campbell wrote:
>>> On Mon, 2013-12-09 at 03:34 +0000, Julien Grall wrote:
>>>> +    BUILD_BUG_ON(p2m_max_real_type > (2 << 4));
>>>
>>> 2<<4 is 32.
>>>
>>> I think you want either 1<<4, 2^4 or just 16 (my preference is 16). And
>>
>> Right.
>>
>>> I think it should be >= since the valid values are 0..15 inclusive.
>>
>> No, because p2m_max_real_type won't be store in the p2m, so we can have
>> 16 values [0..15] and p2m_max_real_type will be the 17th (ie 16).
>
> If p2m_max_real_type will be the 17th (ie 16) then the check needs to be
> p2m_max_real_type >= 16.

No because p2m_max_real_type = 16 is valid.
Which is invalid is foo = 16 and p2m_max_real_type = 17.

-- 
Julien Grall