Am 18.04.2013 um 09:32 schrieb Pranavkumar Sawargaonkar pranavkumar@linaro.org:
On 18 April 2013 12:21, Rusty Russell rusty@rustcorp.com.au wrote:
PranavkumarSawargaonkar pranavkumar@linaro.org writes:
From: Pranavkumar Sawargaonkar pranavkumar@linaro.org
This patch implements early printk support for virtio-mmio console devices without using any hypercalls.
This makes some sense, though not sure that early console *read* makes much sense. I can see the PCI version of this being useful as well.
Read can be useful for "mach-virt" which will have only virtio console as a console device. Then if someone wants to have UEFI or any other boot-loader emulation, which expects user to input few things, in that case read might become handy.
A boot loader should easily be able to implement virtio-console for real.
In fact, you should be able to do a simple virtio-console implementation for early printk too, that polls the host for acks rather than use interrupts. Check out my s390-zipl code for reference. I use that there.
The advantage to that would be that no host changes are required whatsoever and the interface strictly stays as it is.
Alex