On 05/19/2014 02:23 PM, Jörn Engel wrote:
> On Mon, 19 May 2014 17:17:19 -0400, Jörn Engel wrote:
>>
>> Experimentation show this to be an excellent entropy source. Doing 1000
>> boottests with kvm and dumping a hash of the registers for the first
>> 1024 interrupts each, >40% of all hashes were unique and >80% of all
>> hashes occurred less than once 1% of the time.
>
> And since I previously claimed the opposite, the negative result was
> caused by a kvm oddity. When starting kvm in the background, it will
> run just fine. But when starting kvm with "-nographic" in the
> background, the process gets stopped. No output is generated and the
> output file is not even truncated before kvm is stopped. Therefore
> every single run will have identical kernel output - that of the
> previous run.
>
> With that embarrassment out of the way, I find this approach hugely
> valuable. Even if you disagree with some detail of this patch, we
> should definitely merge something roughly related.
>
> Jörn
>
I think this is likely to be particularly valuable during boot. I can
see it becoming substantially less valuable after that point, but during
boot is when the most critical.
What I do see as an issue is that the value is probably impossible to
quantify, and so I feel more than a bit queasy about giving it
/dev/random credit. However, making sure the pool is well stirred
during boot is really way more important.
-hpa
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