Re: [PATCH 0/2] Early printk support for virtio console devices.

From: Rusty Russell
Date: Wed May 01 2013 - 01:31:52 EST


Alexander Graf <agraf@xxxxxxx> writes:
> There are not device specific registers in
> virtio-console. Virtio-console lives behind a virtio bus which doesn't
> know what these registers are.

You're not going to make coherent arguments without reading that actual
patch we're discussing. And you're going to just waste everyone else's
time.

> Even if you shove it into config space,

Which is what the patch does...

> it'd be broken because config access happens without intercepts on
> some platforms.

But people keep assuming it, which is one reason virtio_ccw switched
from passive lguest-style config to active. Only lguest and the old kvm
virtio use it, and lguest can change.

An emergency output is a reasonable idea, and this is a reasonable
implementation. The question is practical: will it be used? Because we
don't implement reasonable ideas which aren't going to be used.

Cheers,
Rusty.
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