Re: [PATCH 5/5] KVM: s390: Split out early console code.

Alexander Graf
2012-10-30T13:43:10Z

On 10/30/2012 01:59 PM, Cornelia Huck wrote:
> On Mon, 29 Oct 2012 19:14:19 +0100
> Alexander Graf<agraf@suse.de> wrote:
>
>> On 29.10.2012, at 14:07, Cornelia Huck wrote:
>>
>>> This code is transport agnostic and can be used by both the legacy
>>> virtio code and virtio_ccw.
>> Would it be possible to actually send real virtio or sclp console commands for early printk? That'd make things a lot easier on the user space end. Combining two completely separate character channels (early printk + sclp or early printk + virtio-console) is really tricky.
>>
> This code is only used if we use a virtio console device. The sclp
> code path is completely different.

Ah, so the sclp early console works differently?

> What do you mean with "real virtio console commands"? The message is
> just put on the output queue anyway.

For virtio-console, yes. For the early printk it is sent to the
hypervisor using a hypercall, not through the virtio queue. So it
arrives at a completely different end point that usually has no
knowledge of the virtio-console output driver.

Alex