Raw HDLC support

modulename: hdlc_raw.ko

configname: CONFIG_HDLC_RAW

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Wan interfaces support
└─>Raw HDLC support
In linux kernel since version 2.6.12  
Generic HDLC driver supporting raw HDLC over WAN connections.

If unsure, say N.

source code:
drivers/net/wan/hdlc_raw.c