OBSD 5.8 and console

[Alessandro Baggi]

Hi list,
I've an APU1D where I want install OpenBSD 5.8 amd64. The only option 
that I have is install from console.

I've downloaded install58.fs and modified /etc/boot.conf adding:
set tty com0
(saved)

During boot it recognizes obsd install media then print this message:
switching to com0

after this I can't receive any output from terminal console (in my case 
screen from linux) and don't know what happen.

Can someone point me in the right direction?

Thanks in advance.