default or selected kernelversion does not have config value CONFIG_BLK_DEV_XPRAM.
Result is shown for kernelversion 6.9.9

XPRAM disk support

modulename: xpram.ko

configname: CONFIG_BLK_DEV_XPRAM

Linux Kernel Configuration
└─>Device Drivers
└─>Block devices
└─>XPRAM disk support
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Select this option if you want to use your expanded storage on S/390
or zSeries as a disk. This is useful as a _fast_ swap device if you
want to access more than 2G of memory when running in 31 bit mode.
This option is also available as a module which will be called
xpram. If unsure, say "N".

source code: