tag	line	file	source code
UART_TX	275	kernel/chr_drv/serial.c	outb_p(info->x_char, UART_TX + info->port);
UART_TX	283	kernel/chr_drv/serial.c	UART_TX + info->port);
UART_TX	359	kernel/chr_drv/serial.c	outb(c, UART_TX + port);
UART_TX	382	kernel/chr_drv/serial.c	queue->buf[head] = inb(UART_TX + port);