Extended 8250/16550 serial driver options

configname: CONFIG_SERIAL_8250_EXTENDED

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>Extended 8250/16550 serial driver options
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
If you wish to use any non-standard features of the standard "dumb"
driver, say Y here. This includes HUB6 support, shared serial
interrupts, special multiport support, support for more than the
four COM 1/2/3/4 boards, etc.

Note that the answer to this question won't directly affect the
kernel: saying N will just cause the configurator to skip all
the questions about serial driver options. If unsure, say N.