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

CONFIG_MACH_BAST_IDE (not configurable)

modulename: bast-ide.ko

configname: CONFIG_MACH_BAST_IDE

Linux Kernel Configuration
└─>SAMSUNG S3C24XX SoCs Support
└─>MACH_BAST_IDE
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
Internal node for machines with an BAST style IDE
interface

source code:
arch/arm/mach-s3c24xx/bast-ide.c