CONFIG_VIODASD is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_VIODASD.
Result is shown for kernelversion 6.2.5

iSeries Virtual I/O disk support

modulename: viodasd.ko

configname: CONFIG_VIODASD

Linux Kernel Configuration
└─>iSeries device drivers
└─>iSeries Virtual I/O disk support
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
If you are running on an iSeries system and you want to use
virtual disks created and managed by OS/400, say Y.

source code: