CONFIG_ALPHA_XL is not available for thedefaultarchitecture x86.
Result is shown for architecture alpha

Alpha-XL

modulename: sys_sio.ko

configname: CONFIG_ALPHA_XL

Alpha system type
└─>Alpha-XL
In linux kernel since version 2.6.12  
XL-233 and XL-266-based Alpha systems.

source code:
arch/alpha/kernel/