The fact that the _devicenode_ exists does not necessarely mean that it is allocated in the kernel. So /dev/ttyS4 may show up with ls but may fail when you try to use it. Check CONFIG_SERIAL_8250_RUNTIME_UARTS in your kernel config file. Most likely place is in /boot.
The user who is to use a serial port should be in the 'dialout' group. Remember that you need to logout/login to make changes in this area effective. Kees -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1087519 Title: Serial port ttyS4 doesn't work in 12.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1087519/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
