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

CONFIG_MACH_BAST_IDE (not configurable)

configname: CONFIG_MACH_BAST_IDE

Linux Kernel Configuration
└─>Samsung S3C24XX SoCs (deprecated, see help)
└─>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