Re: [virtio-dev] Memory sharing device

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Roman Kiryanov (rkir@google.com) wrote:
> > > Our long term goal is to have as few kernel drivers as possible and to move
> > > "drivers" into userspace. If we go with the virtqueues, is there
> > > general a purpose
> > > device/driver to talk between our host and guest to support custom hardware
> > > (with own blobs)?
> >
> > The challenge is to answer the following question:
> > how to do this without losing the benefits of standartization?
> 
> We looked into UIO and it still requires some kernel driver to tell
> where the device is, it also has limitations on sharing a device
> between processes. The benefit of standardization could be in avoiding
> everybody writing their own UIO drivers for virtual devices.
> 
> Our emulator uses a battery, sound, accelerometer and more. We need to
> support all of this. I looked into the spec, "5 Device types", and
> seems "battery" is not there. We can invent our own drivers but we see
> having one flexible driver is a better idea.

Can you group these devices together at all in their requirements?
For example, battery and accelerometers (to me) sound like low-bandwidth
'sensors' with a set of key,value pairs that update occasionally
and a limited (no?) amount of control from the VM->host.
A 'virtio-values' device that carried a string list of keys that it
supported might make sense and be enough for at least two of your
device types.

Dave

> Yes, I realize that a guest could think it is using the same device as
> the host advertised (because strings matched) while it is not. We
> control both the host and the guest and we can live with this.
> 
> Regards,
> Roman.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK