On 22.04.2013, at 05:10, Anup Patel wrote:
On 22 April 2013 06:51, Rusty Russell rusty@rustcorp.com.au wrote:
Pranavkumar Sawargaonkar pranavkumar@linaro.org writes:
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.
But implementing virtio inside a bootloader has already been done for coreboot, for example. A bootloader probably wants a virtio block device, so a console is trivial.
A single writable field for debugging makes sense. Anything more is far less certain.
The early read can be handy for bootloader who don't want to implement complete VirtIO programming.
Virtio is trivial. Seriously. Don't invent new secondary interfaces to the same thing just because you're afraid to write 5 lines of code instead of 2.
Alex
IMHO, early read would be totally optional for host and will not introduce any new config register so it is good to have in VirtIO console spec. Also, without early read the read behavior of early_rw field would be undefined in VirtIO console spec.
Thanks, Rusty.
Best Regards, Anup _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm