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Date:      Sun, 23 Jan 2011 23:03:02 +0300
From:      Alexandr Matveev <timon@timon.net.nz>
To:        Neel Natu <neelnatu@gmail.com>
Cc:        hackers@freebsd.org
Subject:   Re: How to read non-physical memory?
Message-ID:  <4D3C8976.5060109@timon.net.nz>
In-Reply-To: <AANLkTik%2Bzwsh8CCcWkoRHcUZ=BN85BffxcotCbxMBDwH@mail.gmail.com>
References:  <4D3C4F94.7020307@timon.net.nz> <AANLkTik%2Bzwsh8CCcWkoRHcUZ=BN85BffxcotCbxMBDwH@mail.gmail.com>

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On 23.01.2011 22:26, Neel Natu wrote:
> Hi Alexandr,
>
> On Sun, Jan 23, 2011 at 7:56 AM, Alexandr Matveev<timon@timon.net.nz>  wrote:
>> Hello.
>>
>>   When FreeBSD boots with 'boot -v' it show SMAP:
>> SMAP type=01 base=0000000000000000 len=000000000009d800
>> SMAP type=02 base=000000000009d800 len=0000000000002800
>> SMAP type=02 base=00000000000e0000 len=0000000000020000
>> SMAP type=01 base=0000000000100000 len=00000000bfdb0000
>> <...>
>> SMAP type=02 base=00000000fed1c000 len=0000000000004000
>> <...>
>>
>>   Memory range 0xfed1c000 - 0xfed2000 belongs to ICH8 mapped to memory
>> configuration registers.
>>   If I correctly understand mem man page, /dev/mem allow to read only real
>> physical memory. How can I read data from this range?
> I am not sure what the man page says but you can certainly use
> /dev/mem to access mmio space.
>
> I have used 'dd' with 'if=/dev/mem' to dump out mmio registers on
> amd64. YMMV with other architectures.

   Thank you very much.
   dd if=/dev/mem of=mem.dump bs=4 count=4095 skip=1068789760
   works perfectly!

-- 
Alexandr Matveev




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