CONFIG_MACH_AFEB9260 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Custom afeb9260 board v1

modulename: board-afeb-9260v1.ko

configname: CONFIG_MACH_AFEB9260

Linux Kernel Configuration
└─>Atmel AT91 System-on-Chip
└─>Custom afeb9260 board v1
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
Select this if you are using custom afeb9260 board based on
open hardware design. Select this for revision 1 of the board.
<svn://194.85.238.22/home/users/george/svn/arm9eb>
<http://groups.google.com/group/arm9fpga-evolution-board>

source code: