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

[Rusty Russell]

Peter Maydell <peter.maydell at linaro.org> writes:
> On 6 May 2013 06:11, Rusty Russell <rusty at rustcorp.com.au> wrote:
>> Peter Maydell <peter.maydell at linaro.org> writes:
>>> To be actually useful we need to also specify something in
>>> the device tree to say "here is where you will find your
>>> emergency output and what it is".
>>
>> Hmm, I'm not sure that's true.  It looks like it needs:
>>
>> 1) An enhancment to the vdev->set_config callback to pass through (at
>>    least) an offset, probably offset and length.
>>
>> 2) An emerg_write() function ptr which can be called at any time, set by
>>    virtio_console.c's class_init:
>
> That all looks like sensible QEMU implementation possibilities
> but it seems to be a bit of a non-sequitur from "how do we
> tell the kernel to actually use this?"

You enable the feature in the virtio console device, and a kernel
compiled with EARLY_PRINTK will use it?

Cheers,
Rusty.