Am Donnerstag 15 Oktober 2009 20:57:45 schrieb Scott Wood:

Doing it in the backend requires the backend to know whether it's being
called for printk or for user I/O.  In the latter case, we don't want to
spin, but rather wait for an IRQ (or poll with a timer if there's no IRQ).

Right. Now you have me convinced that we really should have some logic in 
hvc_console because, its the only place that knows if it came from printk or 
user.

About the backends, there are some that spin until the text is delivered (e.g. 
virtio) , others can drop (e.g. iucv is a connection oriented protocol and it 
will (and has to) drop if there is no connection).