CONFIG_RPXLITE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_RPXLITE.
Result is shown for kernelversion 5.4.123

RPX-Lite

configname: CONFIG_RPXLITE

8xx Machine Type
└─>RPX-Lite
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
Single-board computers based around the PowerPC MPC8xx chips and
intended for embedded applications. The following types are
supported:

RPX-Lite:
Embedded Planet RPX Lite. PC104 form-factor SBC based on the MPC823.

RPX-Classic:
Embedded Planet RPX Classic Low-fat. Credit-card-size SBC based on
the MPC 860

BSE-IP:
Bright Star Engineering ip-Engine.

TQM823L:
TQM850L:
TQM855L:
TQM860L:
MPC8xx based family of mini modules, half credit card size,
up to 64 MB of RAM, 8 MB Flash, (Fast) Ethernet, 2 x serial ports,
2 x CAN bus interface, ...
Manufacturer: TQ Components, www.tq-group.de
Date of Release: October (?) 1999
End of Life: not yet :-)
URL:
- module: <http://www.denx.de/PDF/TQM8xxLHWM201.pdf>
- starter kit: <http://www.denx.de/PDF/STK8xxLHWM201.pdf>
- images: <http://www.denx.de/embedded-ppc-en.html>

FPS850L:
FingerPrint Sensor System (based on TQM850L)
Manufacturer: IKENDI AG, <http://www.ikendi.com/>
Date of Release: November 1999
End of life: end 2000 ?
URL: see TQM850L

IVMS8:
MPC860 based board used in the "Integrated Voice Mail System",
Small Version (8 voice channels)
Manufacturer: Speech Design, <http://www.speech-design.de/>
Date of Release: December 2000 (?)
End of life: -
URL: <http://www.speech-design.de/>

IVML24:
MPC860 based board used in the "Integrated Voice Mail System",
Large Version (24 voice channels)
Manufacturer: Speech Design, <http://www.speech-design.de/>
Date of Release: March 2001 (?)
End of life: -
URL: <http://www.speech-design.de/>

HERMES:
Hermes-Pro ISDN/LAN router with integrated 8 x hub
Manufacturer: Multidata Gesellschaft fur Datentechnik und Informatik
<http://www.multidata.de/>
Date of Release: 2000 (?)
End of life: -
URL: <http://www.multidata.de/english/products/hpro.htm>

IP860:
VMEBus IP (Industry Pack) carrier board with MPC860
Manufacturer: MicroSys GmbH, <http://www.microsys.de/>
Date of Release: ?
End of life: -
URL: <http://www.microsys.de/html/ip860.html>

PCU_E:
PCU = Peripheral Controller Unit, Extended
Manufacturer: Siemens AG, ICN (Information and Communication Networks)
<http://www.siemens.de/page/1,3771,224315-1-999_2_226207-0,00.html>
Date of Release: April 2001
End of life: August 2001
URL: n. a.