tag	line	file	source code
UART_TX	281	kernel/chr_drv/serial.c	serial_outp(info, UART_TX, info->x_char);
UART_TX	288	kernel/chr_drv/serial.c	serial_outp(info, UART_TX,
UART_TX	425	kernel/chr_drv/serial.c	serial_outp(info, UART_TX, info->x_char);
UART_TX	435	kernel/chr_drv/serial.c	serial_outp(info, UART_TX, queue->buf[tail++]);