Re: [Tails-dev] from sdmem to memtest, and testing procedure…

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Autor: intrigeri
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Dla: The Tails public development discussion list
Temat: Re: [Tails-dev] from sdmem to memtest, and testing procedures
anonym wrote (30 Dec 2011 13:52:08 GMT) :
> 12/28/2011 11:53 PM, intrigeri:
>> Hi,
>>
>> as far as Tails is concerned, I'm thinking of:
>>   - on 64-bit hardware, kexec to a 64-bit kernel and use memtest=
>>     there; Maxim, have you confirmed by actual testing this works for
>>     more than 3GB?


> I just tried your implementation of this in the bugfix/kexec_amd64
> branch


Seems like there's been some misunderstanding.
The bugfix/kexec_amd64 is no implementation of this.
The bugfix/kexec_amd64 branch merely does the same sdmem thing as was
done in Tails 0.9, but kexec's on a 64-bit kernel on 64-bit hardware,
in the hope it makes sdmem wipe more memory.

> on bare-metal, and I'm sad to say that it's not working. The
> following lists the number of occurrences of the pattern for certain
> segments of memory (in megabytes):


> 0   -  10: 348
> 10  -  20: 244233
> 30  - 200: 0
> 200 - 600: each 10 MB block in this segment has ~655K hits*
> 600 -2180: 0
> 2180-2190: 511
> 2190-2330: 0
> 2330-2340: 174
> Rest     : 0


> * Note that a 10 MB block can contain at most 655360 occurrences of a
> 16 byte pattern (like ours) so this memory segment is completely
> untouched by the wipe.


Ok. This is a problem, and tends to show that branch does not help
that much. Let's postpone this to post-0.10 days.

Cheers,
--
intrigeri <intrigeri@???>
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