Hello, I am trying to use a serial port in linux. My architecture is: -compaq evo n600c -debian GNU Linux 3.1 -vanilla kernel: Linux furge 2.6.21 #2 SMP Sat Jun 2 21:25:42 CEST 2007 i686 GNU/Linux This is my dmesg output: serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A serial8250: ttyS2 at I/O 0x3e8 (irq = 3) is a 16550A 00:02: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A I am trying to test the serial port by jumpering the receive and transmit pins of the serial port. Using this hardware, windows XP serial port tester program echos back the characters written to the port, so the hardware is ok. However, in Linux, the port stays dumb. I can write to it, but there is nothing to be read from it. e.g. cat /dev/ttyS0 > /tmp/serial.txt &; echo "a" > /dev/ttyS0; cat /tmp/serial.txt or cp /dev/ttyS0 /dev/tty1; echo "a" > /dev/ttyS0 I have read through the "Cannot write but not read" topic in this mailing list, but without any success. Also I have tried several serial port testing programs, all in vain. Kernel recompilations made no luck. I would really appreciate your help, Thanks, Gabor - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html