Messages in this thread | | | Date | Fri, 26 Apr 2013 16:54:01 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH 0/2] Early printk support for virtio console devices. |
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On 26/04/13 16:03, Arnd Bergmann wrote: > On Friday 26 April 2013, Anup Patel wrote: >> I am curious about how smh-based or hypercall-based early prints would >> be handled in following scenario: >> >> "A board is running KVM ARM enabled kernel and linux console on serial >> port. Now a user remotely connects to the board via telnet/ssh and >> launches a VM with smh-based or hypercall-based earlyprintk." >> >> In the above scenario, will smh-based or hypercall-based earlyprints >> appear to user on remote shell or not ? > > The implementation of the console device would still be done by KVM, > as for any other virtual device, so it shows up whereever kvm is > configured to output the console data.
Actually, at least in the case of smh-based earlyprintk, the output only appears in the model console, and never reach the rest of the kernel.
And any other non-MMIO approach (like a hypercall) will be very hard to feed back to the console, as KVM itself has no idea of what a "console" is. You'd need another side channel to userspace, hoping that it will be able to merge the multiple streams.
M. -- Jazz is not dead. It just smells funny...
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