CONFIG_MACH_OSIRIS is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Simtec IM2440D20 (OSIRIS) module

modulename: mach-osiris.ko

configname: CONFIG_MACH_OSIRIS

Linux Kernel Configuration
└─>S3C24XX Implementations
└─>Simtec IM2440D20 (OSIRIS) module
In linux kernel since version 2.6.17 (release Date: 2006-06-17)  
Say Y here if you are using the Simtec IM2440D20 module, also
known as the Osiris.

source code:
arch/arm/mach-s3c2410/mach-osiris.c