Description:
When MFP_DEBUG_DIRECT isn't defined, BIOS function "Bconout( )" is
called to output debug messages. During initialization until all
interrupts vectors and new trap routines are initialized this function
is used through a normal trap, and later trough a trap wrapper. The
flag "intr_done" is activated to mark this point. During the boot
process the macro DEBUG is used after interrupts initialization and
before the flag is activated, this makes the kernel crash when using
serial debugging with "Bconout( )".