Re: [Qemu-devel] [PATCH 2/2] VirtIO RNG

[Ian Molton]

Paul Brook wrote:
>>>>        This patch adds support for virtio-rng. Data is read from a
>>>> chardev and can be either raw entropy or received via the EGD protocol.
>>> I still don't get why you need this at all. It seems like
>>> virtio-serial would already provides everything you need.
>> I guess when virtio-rng was first written, virtio-serial wasn't
>> flexible enough because it didn't support multiple devices 
> 
> That argument no longer holds.

So now everything that looks like a stream of bytes has to use the
virtio-serial code...

Why? Its not like it'll make the rng device any simpler, smaller,
faster, or reduce its dependencies. Virtio is simple enough to begin with!

>> and maybe virtio-rng is still needed to enforce the EGD protocol when that
>> is being used.
> 
> Maybe, though the benefit of having this knowledge in wemu seems somewhat 
> unclear. If we do want it then shouldn't be be implemented as a char device 
> backend, rather than part of a specific serial port implementation?

Be my guest...

> gettimeofday can and does jump arbitrarily. Comparing returned values is 
> almost always wrong.

True, however the worst case is still a very temporary over-alotment of
entropy, which really isn't a problem.

-Ian