Re: [PATCH 2/2] random: Account for entropy loss due to overwrites

[H. Peter Anvin]

On 04/25/2013 07:38 AM, Linus Torvalds wrote:
> This doesn't work AT ALL. You even hint at the reason why in your message.
> 
> On Tue, Apr 23, 2013 at 9:26 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>>
>> As such, this conservatism seems more than justified.  Note, however,
>> that attempting to add one bit of entropy will never succeed; nor will
>> two bits unless the pool is completely empty.  These roundoff
>> artifacts could be improved by using fixed-point arithmetic and adding
>> some number of fractional entropy bits.
> 
> Take a look at "add_interrupt_randomness()". Hmm..
> 

<facepalm>

Right.  Before July of last year add_interrupt_randomness() called
add_timer_randomness() which credits up to 11 bits, but not anymore.

-ESTALEBRAIN.

OK, so we need to track fractional bits.

	-hpa


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/