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

LaCie Big Disk Network

modulename: d2net-setup.ko

configname: CONFIG_MACH_BIGDISK

Linux Kernel Configuration
└─>Orion Implementations
└─>LaCie Big Disk Network
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
Say 'Y' here if you want your kernel to support the
LaCie Big Disk Network NAS.

source code:
/arch/arm/mach-orion5x/d2net-setup.c