Re: Serial Port COM1 under Linux on IBM ThinkPad 770X

Linux Lists (lists@cyclades.com)
Fri, 2 Jul 1999 09:20:45 -0700 (PDT)


On Fri, 2 Jul 1999, Dirk W. Steinberg wrote:
>
> root@ibmtop:pts/0 ~ # ll /dev/ttyS[01]
> 0 crw-rw---- 1 root dialout 4, 64 Feb 23 04:42 /dev/ttyS0
> 0 crw-rw---- 1 root dialout 4, 65 Feb 23 04:42 /dev/ttyS1
> root@ibmtop:pts/0 ~ # cu -l /dev/ttyS0
> cu: open (/dev/ttyS0): Permission denied
> cu: /dev/ttyS0: Line in use
> zsh: 5731 exit 1 cu -l /dev/ttyS0

<snip>

> 8. Finally I tried this:
>
> root@ibmtop:pts/0 ~ # chmod 777 /dev/ttyS[01]
> root@ibmtop:pts/0 ~ # setserial -av -z /dev/ttyS0 port 0x03f8 auto_irq autoconfig
> /dev/ttyS0, Line 0, UART: unknown, Port: 0x03f8, IRQ: 4
> Baud_base: 115200, close_delay: 50, divisor: 0
> closing_wait: 3000, closing_wait2: infinite
> Flags: spd_normal auto_irq
>
> root@ibmtop:pts/0 ~ # cu -l /dev/ttyS0
> Connected.
> cu: Got hangup signal
>
> Disconnected.

The problem is not in the serial driver, neither with your notebook, but
with the cu application (AFAIK). If you tried minicom, it would have
probably work with the previous permissions. cu requires the device to be
accessible by the uucp group. A permission set that works with everything
I tried (as I found out from Red Hat 6.0), including cu, is:

[ivan@kelly ivan]$ ls -l /dev/ttyC0
crw-rw---- 1 uucp uucp 19, 0 jun 28 17:15 /dev/ttyC0

I'm showing a Cyclades serial port device, but if you change the
permissions on the standard serial port to those (actually, this is how it
is on Red Hat 6.0), then cu will work fine.

Hope it helps.

Regards,
Ivan

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