x86: realmode: fix serial_init()

In some setups serial output from the real-mode tests is corrupted.

I do not know the serial port initialization code well, but the protected mode initialization code is different than the real-mode code. Using the protected mode serial port initialization fixes the problem.

Keeping the tradition of code duplication between real-mode and protected mode, this patch copies the missing initialization into real-mode serial port initialization.

---
 x86/realmode.c | 9 +++++++++
 1 file changed, 9 insertions(+)

index 90ecd13..7c2d776 100644
@@ -77,6 +77,15 @@ static void serial_init(void)
 	lcr = inb(serial_iobase + 0x03);
 	lcr &= ~0x80;
 	outb(lcr, serial_iobase + 0x03);
+
+	/* IER: disable interrupts */
+	outb(0x00, serial_iobase + 0x01);
+	/* LCR: 8 bits, no parity, one stop bit */
+	outb(0x03, serial_iobase + 0x03);
+	/* FCR: disable FIFO queues */
+	outb(0x00, serial_iobase + 0x02);
+	/* MCR: RTS, DTR on */
+	outb(0x03, serial_iobase + 0x04);
 }
 #endif
 

2.17.1