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

[Pranavkumar Sawargaonkar]

Hi Will,
On 19 April 2013 14:35, Will Deacon <will.deacon at arm.com> wrote:
> Hello,
>
> On Thu, Apr 18, 2013 at 09:48:49AM +0100, Pranavkumar Sawargaonkar wrote:
>> Actually i thought adding a config register will be easier to add a
>> code than writing entire emulation as 8250 emulation will require to
>> deal with dealing with more registers and more code.
>
> kvmtool already has an 8250 emulation! All we need to do is hack together
> something which will allow us to instantiate those ioport devices in a more
> flexible manner (namely, inside the MMIO space for ARM). For earlyprintk, I
> suspect we can get away without an interrupt too, which should simplify
> things a bit to start with.
>
> Regardless of the outcome of this discussion, I think getting the 8250
> working on ARM is definitely something worth doing. If I get time, I'll take
> a look.

I am not against using 8250 emulation (as far as it solves printk
issues for kernel booting logs), but my point is why not to add early
read-write support for virtio console, which also can be useful in
emulation less mach-virt environment also ?

Thanks,
Pranav

>
> Will