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Date: Thu, 04 Apr 2013 09:17:27 +0800
From: Simon Jeons <simon.jeons@...il.com>
To: "H. Peter Anvin" <hpa@...or.com>
CC: Frantisek Hrbata <fhrbata@...hat.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
oleg@...hat.com, kamaleshb@...ibm.com, hechjie@...ibm.com
Subject: Re: [PATCH] x86: add phys addr validity check for /dev/mem mmap
Hi H.Peter,
On 04/04/2013 09:13 AM, H. Peter Anvin wrote:
> On 04/03/2013 06:11 PM, Simon Jeons wrote:
>> Why we consider boot_cpu_data.x86_phys_bits instead of e820 map here?
>>
> Because x86_phys_bits is what controls how much address space the
> processor has. e820 tells us how much *RAM* the machine has, or
> specifically, how much RAM the machine had on boot.
e820 also contain mmio, correct? So cpu should not access address beyond
e820 map(RAM+MMIO).
>
> -hpa
>
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