Messages in this thread | | | From | Alexander Graf <> | Subject | Re: [RFC] arm64: Early printk support for virtio-mmio console devices. | Date | Thu, 18 Apr 2013 10:44:32 +0200 |
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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
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