I have recently tried to breathe life to the serial port of my DELL D630 notebook under Ubuntu Natty, but the opening always failed with I/O error.

I have tried the relevant acpi=off, pnpacpi=off kernel parameters, updated the BIOS, but these thigns did not lead to succes. As final trying I have switched the port from COM1 to COM2 int the BIOS and finally it became available as /dev/ttyS1