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Message-ID: <516626E4.4000507@gmail.com>
Date: Thu, 11 Apr 2013 10:58:44 +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
Subject: Re: [PATCH] x86: add phys addr validity check for /dev/mem mmap
Hi H.Peter,
On 04/11/2013 10:48 AM, H. Peter Anvin wrote:
> On 04/10/2013 07:40 PM, Simon Jeons wrote:
>> 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.
>> I have 8GB memory in my machine, but when I accumulated every e820
>> ranges which dump in dmesg, there are 25MB memory less then 8GB(1024*8)
>> memory, why 25MB miss?
>>
> For whatever reason your BIOS is stealing some memory, possibly for video.
Thanks for your quick response. ;-)
My machine is new which have i7 cpu. How much memory video need? 8MB?
Why I miss 25MB?
>
> -hpa
>
>
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