On 22.04.2013, at 05:10, Anup Patel wrote: > On 22 April 2013 06:51, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: >> >> Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx> writes: >>> On 18 April 2013 12:21, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: >>>> >>>> PranavkumarSawargaonkar <pranavkumar@xxxxxxxxxx> writes: >>>>> From: Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx> >>>>> >>>>> 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@xxxxxxxxxxxxxxxxxxxxx > https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
