tag	line	file	source code
UART_MCR_LOOP	1150	kernel/chr_drv/serial.c	outb_p(UART_MCR_LOOP | scratch, UART_MCR + port);
UART_MCR_LOOP	1152	kernel/chr_drv/serial.c	outb_p(UART_MCR_LOOP | 0x0A, UART_MCR + port);