Re: random: Providing a seed value to VM guests

["H. Peter Anvin" <hpa@zytor.com>]

On 05/01/2014 03:32 PM, Andy Lutomirski wrote:
> On Thu, May 1, 2014 at 3:28 PM,  <tytso@mit.edu> wrote:
>> On Thu, May 01, 2014 at 02:06:13PM -0700, Andy Lutomirski wrote:
>>>
>>> I still don't see the point.  What does this do better than virtio-rng?
>>
>> I believe you had been complaining about how complicated it was to set
>> up virtio?  And this complexity is also an issue if we want to use it
>> to initialize the RNG used for the kernel text ASLR --- which has to
>> be done very early in the boot process, and where making something as
>> simple as possible is a Good Thing.
> 
> It's complicated, so it won't be up until much later in the boot
> process.  This is completely fine for /dev/random, but it's a problem
> for /dev/urandom, ASLR, and such.
> 
>>
>> And since we would want to use RDRAND/RDSEED if it is available
>> *anyway*, perhaps in combination with other things, why not use the
>> RDRAND/RDSEED interface?
> 
> Because it's awkward.  I don't think it simplifies anything.
> 

It greatly simplifies discovery, which is a Big Deal[TM] in early code.

	-hpa