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Re: Does reboot clear RAM?
From: |
Narcis Garcia |
Subject: |
Re: Does reboot clear RAM? |
Date: |
Wed, 13 Nov 2019 09:58:08 +0100 |
El 13/11/19 a les 7:27, Joachim Durchholz ha escrit:
> Am 12.11.19 um 02:20 schrieb Jakob Bohm:
>> On 11/11/2019 20:27, Joachim Durchholz wrote:
>>> Am 11.11.19 um 15:35 schrieb Jakob Bohm:
>>>> On physical machines, the following mechanisms are common:
>>>>
>>>> 1. DRAM chips physically loose their contents after a few seconds of
>>>> power
>>>> off,
>>>
>>> I am by no way an expert, but the forensic experts tell me that data
>>> can persist for *minutes*.
>>> Of course, the first bits flip after a few seconds. But you don't get
>>> a guarantee that everything is zeroed.
>>> I also hear that temperature plays a really big role here.
>>>
>> There's a difference between reading faded bits with special analogue
>> equipment
>> after artificially cooling chips way below what the datasheet allows, and
>> reading the digital bits at normal temperature, voltage etc.
>
> The refresh circuitry of a DRAM chip is just for the purpose of reading
> faded bits.
> And of course it will read whatever it decides is in the cell. If enough
> electrons are left, it will be above the threshold, so you can expect to
> see the occasional 1 bit in RAM unless it's cleared.
>
> I'm still interested in hearing whether typical RAM has a RST line and
> whether that wipes memory (or merely initializes internal circuitry).
> Speculation about potential low-level circuit trickery is nice but does
> not answer that question, I fear.
I think the best solution is to implement:
- A flag/parameter to reboots do clear RAM
- A flag/parameter to reboots don't clear RAM
- A default behaviour.
Default behaviour could depend on specified chipset or other virtualized
hardware if that originally have different behaviour.
- Re: Does reboot clear RAM?, (continued)
- Re: Does reboot clear RAM?, Narcis Garcia, 2019/11/09
- Re: Does reboot clear RAM?, Joachim Durchholz, 2019/11/10
- Re: Does reboot clear RAM?, Kent Dorfman, 2019/11/10
- Re: Does reboot clear RAM?, Joachim Durchholz, 2019/11/11
- Re: Does reboot clear RAM?, Jakob Bohm, 2019/11/11
- Re: Does reboot clear RAM?, Joachim Durchholz, 2019/11/11
- Re: Does reboot clear RAM?, Jakob Bohm, 2019/11/11
- Re: Does reboot clear RAM?, Narcis Garcia, 2019/11/12
- Re: Does reboot clear RAM?, Peter Maydell, 2019/11/12
- Re: Does reboot clear RAM?, Joachim Durchholz, 2019/11/13
- Re: Does reboot clear RAM?,
Narcis Garcia <=
- Re: Does reboot clear RAM?, Marc-André Lureau, 2019/11/13