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

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Author: intrigeri
Date:  
To: Maxim Kammerer
CC: The Tails public development discussion list
Subject: Re: [Tails-dev] from sdmem to memtest, and testing procedures
Hi,

Maxim Kammerer wrote (25 Dec 2011 22:52:52 GMT) :
> When replacing an initramfs-based memwipe process with memtest, I of
> course tested the functionality using pmemsave in QEMU, and found
> that absolutely all RAM that I could fill before booting into the
> KEXEC kernel was wiped correctly (and I checked that none of it was
> wiped with memtest=0).


Ok. Do you confirm one may test this on Liberté 2011.2 as follows?

  1. write a known string numerous times in RAM
  2. enter the bottom-left menu
  3. select "Logout"
  4. select "Reboot"
  5. as soon as I see qemu trying to netboot, I may assume the
     kexec+memtest thing is supposed to be done
  6. pmemsave + grep -c


... or is memtest only used on shutdown?

> I don't see any reason to assume that the regions must be contiguous,
> as there is probably some address translation going on.


Right. Thanks for noticing it.

> However, I didn't test with QEMU memory sizes over 512 MiB, so that
> might be the problem. Did you experience the same problems with
> memories in the ballpark of 512 MiB?


I did not even try. Since our goal was to fix the known existing flaws
in the Tails memory wiping process (flaws that are in the 3-4GiB area,
as you know), I only run my tests against systems with at least 4GiB.

Regards,
--
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