start.S 0x480 add 4 ins to need jump to 0x80008000.
	dmtc0 k0, $31
	li k0, 0x80008000
	jr k0
	dmtc0 k0, $31
pmon:
call 0x80008010 will enter kgdb
input $3#33 back to cmdline ,or gdb target remote /dev/ttyUSB0 to debug.

linux:
app run sdbbp will enter kgdb.

gdb:
support b,hb,watch,rwatch,awatch,monitor
monitor cmd to run builtin some cmd.

linux simple enter ejtag code see break.S
to compile break.S:
	$(CROSS_COMPILE)gcc -mabi=32 -c break.S
	$(CROSS_COMPILE)ld -m elf32ltsmip -s  -o break.out -e _start break.o

if pmon does not copy gdbstub.bin64 to 0x80000000, we also can use kgdbstub.bin64.

we can setup gdbstub.bin64 in pmon or linux cmdline.
debug pmon,kernel by serial does not need os support.

kernel:
./ejtaginit.sh ls2k
./break.out
pmon: upload gdbstub.bin64
ymodem base=0x80008000
call 0x80008008
call 0x80008010
