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Re: [Xen-devel] [PATCH] cleanup for __start_xen()

To: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>, Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] cleanup for __start_xen()
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Mon, 30 Nov 2009 18:52:41 +0000
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On 30/11/2009 17:42, "Ian Jackson" <Ian.Jackson@xxxxxxxxxxxxx> wrote:

> I wrote:
>> Xiao Guangrong writes ("[Xen-devel] [PATCH] cleanup for __start_xen()"):
>>> -        if ( !initial_images_start && (s < e) &&
>>> +        if ( !initial_images_start &&
>> This is wrong.  s and e are uint64_t so if !(s < e), (e-s) will be
>> large and positive.
> I see this has already been applied (20523).  It should be reverted, I
> think.

None of the if() blocks in the loop will make e<s, as that would imply that
the block had allocated itself a chunk of memory that starts below s. So it
is actually safe to remove the checks, as we know e>=s. But now I look at it
I think I broke the module-relocation block some time ago -- it ends up with
'e' being too large by modules_headroom. :-( Will look into that more

 -- Keir

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