CONFIG_MARCH_Z900 is not available for thedefaultarchitecture x86.
Result is shown for architecture s390

IBM zSeries model z800 and z900

configname: CONFIG_MARCH_Z900

Processor type
└─>IBM zSeries model z800 and z900
In linux kernel since version 2.6.12  
Select this to enable optimizations for model z800/z900 (2064 and
2066 series). This will enable some optimizations that are not
available on older ESA/390 (31 Bit) only CPUs.


depends
CONFIG_cc-option