[vbox-dev] virtio-rng et al

Johannes Ernst johannes.ernst at gmail.com
Wed Mar 4 15:48:24 UTC 2015

Unfortunately this is a headless server that wants to spin up and down a large number of VMs in short sequence as part of a QA process. Each wants to generate some key pairs. So banging on the keyboard or such isn't an option.

Sent from my iPad.

> On Mar 4, 2015, at 01:58, Frank Mehnert <frank.mehnert at oracle.com> wrote:
> I think the same you would do on real hardware. When I create crypt keys
> on real hardware on Linux I'm asked to perform some actions like pressing
> random keys very fast. I guess a busy (virtual) hard disk would add more
> entropy, same with a busy network interface. Such device activities should
> trigger a lot of interrupts which can be used by the guest OS kernel to
> generate more entropy.
> Frank
>> On Wednesday 04 March 2015 00:10:09 you wrote:
>> So in a nutshell, what's the best I can do at this point without code
>> changes or waiting for the next release? I'm attempting to generate some
>> gpg keys etc and it's taking a loooong time....
>> Sent from my iPad.
>>> On Mar 3, 2015, at 23:55, Frank Mehnert <frank.mehnert at oracle.com> wrote:
>>> Johannes,
>>>> On Tuesday 03 March 2015 20:31:06 Johannes Ernst wrote:
>>>> What’s the best source of randomness for a Linux guest?
>>>> I’ve been reading about virtio-rng [1]. Can it be made to work with
>>>> VirtualBox?
>>> VirtualBox does not support virtio-rng but I guess it's not very
>>> difficult to add this feature. I'm more worried about support for
>>> hosts/guests different than Linux.
>>> The source for entropy in a virtual machine is in principle the
>>> same like on bare metal, for instance device interrupts and their
>>> distribution over time, several clocks and the time stamp counter.
>>> VirtualBox tries very hard (and this will be even improved in the
>>> next major release) to provide the guest sensible values when
>>> reading the time stamp counter using the RDTSC machine instruction.
>>> But I admit that the sources for entropy within a virtual machine
>>> are limited in comparison to bare metal, mainly because a guest
>>> is usually configured to have only access to virtual devices being
>>> essential for doing it's job.
>>> Frank
> -- 
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