todo

rtlinux3.0 的源代码

- /dev/ttyS0 should correspond not to the first entry in the table,
but to the real COM1. We can implement rt_com_setserial that
would set parameters. Or we can use module parameters:
insmod rt_com com1=0x2f8,4
Only those ports listed on the command line would be requested

- POSIX tcgetattr/tcsetattr (non-canonical mode only)