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.