Re: [Qemu-devel] [RFC] Virtio RNG: Consider changing the default entropy source to /dev/urandom?

[Kashyap Chamarthy]

On Fri, Sep 21, 2018 at 08:06:24PM +0200, Laszlo Ersek wrote:
> On 09/21/18 17:43, Kashyap Chamarthy wrote:

[...]

> > (b) When QEMU exposes a Virtio RNG device to the guest, that device
> >     needs a source of entropy, and IIUC, that source needs to be
> >     "non-blocking" (i.e. `/dev/urandom`).  However, currently QEMU
> >     defaults to the problematic `/dev/random`.
> > 
> > I'd like to get some more clarity on case (b).  
> > 
> > 
> > [1] https://lists.nongnu.org/archive/html/qemu-devel/2018-06/msg08335.html
> >     -- RNG: Any reason QEMU doesn't default to `/dev/urandom`
> > 
> > [2] http://man7.org/linux/man-pages/man4/urandom.4.html
> > 
> > 
> 
> The libvirt domain documentation <https://libvirt.org/formatdomain.html>
> also says,
> 
> "When no file name is specified, the hypervisor default is used. For
> QEMU, the default is /dev/random. However, the recommended source of
> entropy is /dev/urandom (as it doesn't have the limitations of
> /dev/random)."

It so happens that I updated that specific piece of documentation, after
a chat with Dan Berrangé. :-)

-- 
/kashyap