Linux 2.6-10.rc3 8xx: Only 3 characters are printed well in __i n it start_kernel() upon kernel booting

__init start_kernel() in init/main.c 

... 
lock_kernel();
page_address_init();
printk(linux_banner);
setup_arch(&command_line);
setup_per_cpu_areas();
...

Are interrupts enabled in above code ?
If so, could I somehow disable interrupts and switch to the "polling mode"
of the serial driver (drivers/serial/cpm_uart/cpm_uart_core.c) just before
printk() ?

Thanks,
Alex