[RFC] arm64: Early printk support for virtio-mmio console devices.

[Peter Maydell]

On 19 April 2013 18:14, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Fri, Apr 19, 2013 at 05:33:18PM +0100, Peter Maydell wrote:
>> The command line lives in the DTB anyway so if you can't look
>> in the DTB you can't get at earlyprintk config either way.
>
> Linux indeed looks in the DT for the command line and that's what's
> triggering the earlyprintk console but at that stage the DT is flat.
> Unflattening the DT happens later (it requires slab allocator). I
> initially thought about extracting the early console device from the DT
> but when it is flat you can't parse the full hierarchy to get its
> address.

So you could add a DT property that specifies the information in a
format that you can get at at the right time. That's annoying
duplication, but at least it's not in the command line (which is
a raw ascii string that QEMU &co shouldn't have to be parsing or
editing). "/console/type" and "/console/address" or something?

-- PMM