CONFIG_VIOTAPE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

iSeries Virtual Tape Support

modulename: viotape.ko

configname: CONFIG_VIOTAPE

Linux Kernel Configuration
└─>iSeries device drivers
└─>iSeries Virtual Tape Support
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
If you are running Linux on an iSeries system and you want Linux
to read and/or write a tape drive owned by OS/400, say Y here.

source code: