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Subject: Re: [PATCH] mm,x86: fix span coverage in e820_all_mapped()
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Tue, 10 Dec 2013 17:06:36 -0800
To: Yinghai Lu <yinghai@kernel.org>
CC: Xishi Qiu <qiuxishi@huawei.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        the arch/x86 maintainers <x86@kernel.org>, Linn Crosetto <linn@hp.com>,
        Pekka Enberg <penberg@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux MM <linux-mm@kvack.org>
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Ok, the issue I thought we were discussing was actually [A,B) [B,C) [C,D) ...

Yinghai Lu <yinghai@kernel.org> wrote:
>On Tue, Dec 10, 2013 at 2:51 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 12/10/2013 01:52 PM, Yinghai Lu wrote:
>>>>
>>>> What happens if it spans more than two regions?
>>>
>>> [A, B), [B+1, C), [C+1, D) ?
>>> start in [A, B), and end in [C+1, D).
>>>
>>> old code:
>>> first with [A, B), start set to B.
>>> then with [B+1, C), start still keep as B.
>>> then with [C+1, D), start still keep as B.
>>> at last still return 0...aka not_all_mapped.
>>>
>>> old code is still right.
>>>
>>
>> Why not_all_mapped?
>
>[B, B+1), and [C, C+1) are not there.

-- 
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