CONFIG_MIPS_COBALT is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Support for Cobalt Server

modulename: fixup-cobalt.ko

configname: CONFIG_MIPS_COBALT

System type
└─>Support for Cobalt Server
In linux kernel since version 2.6.12  
source code:
arch/mips/pci/fixup-cobalt.c