CONFIG_HP_SIMSERIAL is not available for thedefaultarchitecture x86.
Result is shown for architecture ia64

Simulated serial driver support

modulename: simserial.ko

configname: CONFIG_HP_SIMSERIAL

Linux Kernel Configuration
└─>HP Simulator drivers
└─>Simulated serial driver support
In linux kernel since version 2.6.12  
source code:
arch/ia64/hp/sim/simserial.c