CONFIG_MIPS_COBALT is not available for the selected architecture x86.
Result is shown for architecture mips

Cobalt Server

modulename: fixup-cobalt.ko

configname: CONFIG_MIPS_COBALT

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