CONFIG_ARCH_BAST is not available for the default architecture x86.
Result is shown for architecture arm

Simtec Electronics BAST (EB2410ITX)

modulename: mach-bast.ko
configname: CONFIG_ARCH_BAST

Linux Kernel Configuration
└─> SAMSUNG S3C24XX SoCs Support
└─> Simtec Electronics BAST (EB2410ITX)

Say Y here if you are using the Simtec Electronics EB2410ITX
development board (also known as BAST)

source code: