[Question] How can the console be attached to display/keyboard?

[SimonGuo]

Hi dear alias,

I am using a powerPC server, who has some issue with its serial 
hardware.  I have physically connected display/keyboard to the server. 
And when machine starts, the petitboot screen appears at display and can 
be controlled by keyboard.

But after I choose the Ubuntu version in the petitboot , and press 
"enter", the console is redirected into serial console. Then the control 
was lost.

What parameter I can use to attach the output/input to physical 
display/keyboard?

Thanks,
Simon