Features/gdbstub
QEMU support a gdbserver known as the gdbstub. With this you can debug programs in both linux-user and system emulation modes.
Invoking
$QEMU $QEMU_ARGS -s -S
Will configure the system and stop at the first instruction. You can then attach with:
gdb $BINARY -ex "target remote localhost:1234"
and debug your program
Developer Notes
The gdbstub doesn't support all the features of the gdbserver protocol which is documented here