CONFIG_PPC_ISERIES is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_PPC_ISERIES.
Result is shown for kernelversion 6.2.5

IBM Legacy iSeries

configname: CONFIG_PPC_ISERIES

Linux Kernel Configuration
└─>IBM Legacy iSeries
In linux kernel since version 2.6.15 (release Date: 2006-01-02)