Re: [Xen Hackathon] new PV drivers

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 06/09/2014 10:43 AM, Ian Campbell wrote:
> On Mon, 2014-06-09 at 10:39 -0400, Boris Ostrovsky wrote:
>> On 06/09/2014 10:33 AM, Ian Campbell wrote:
>>> On Mon, 2014-06-09 at 10:30 -0400, Boris Ostrovsky wrote:
>>>> On 06/09/2014 05:42 AM, Stefano Stabellini wrote:
>>>>> On Mon, 9 Jun 2014, Ian Campbell wrote:
>>>>>> On Fri, 2014-06-06 at 14:56 +0100, Anil Madhavapeddy wrote:
>>>>>>> On 3 Jun 2014, at 12:47, Stefano Stabellini <stefano.stabellini@eu.citrix.com> wrote:
>>>>>>>
>>>>>>>> Present (by memory):
>>>>>>>> - Julien Grall,
>>>>>>>> - Stefano Stabellini,
>>>>>>>> - Ian Campbell,
>>>>>>>> - Roger Pau Monne,
>>>>>>>> - Dario Faggioli,
>>>>>>>> - Andrii Tseglytskyi,
>>>>>>>> - David Vrabel,
>>>>>>>> - Konrad Wilk.
>>>>>>>>
>>>>>>>> * What new PV devices do we need? What has been done already?
>>>>>>> I missed this session, but was wondering about an entropy driver.
>>>>>>> We're integrating an OCaml SSL/TLS into MirageOS, and it's not clear
>>>>>>> how PV guests should go about getting a strong source of entropy from
>>>>>>> the outside world in a reasonably portable way.
>>>> Is entropy provided by drivers/char/random.c not sufficient?
>>> This is about providing entropy for that driver to consume.
>>>
>>> VMs typically don't have much hardware and therefore don't have much
>>> entropy to seed the pool with.
>> So this is about seeding, not feeding? (sorry, did not mean to start
>> rhyming ;-)).
> TBH I'm not sure, I think it could be either or both...

Feeding is done by interrupt timing and block device access latency, 
both of which are happening in a guest. I don't know whether there is 
enough of that but perhaps before embarking on new PV driver it may be 
worth investigating quality of existing entropy source. Or maybe it's 
already been looked at.

-boris