CONFIG_ETRAX_CARDBUS is not available for thedefaultarchitecture x86.
Result is shown for architecture cris
default or selected kernelversion does not have config value CONFIG_ETRAX_CARDBUS.
Result is shown for kernelversion 6.7-rc3

Cardbus support

modulename: bios.ko

configname: CONFIG_ETRAX_CARDBUS

Linux Kernel Configuration
└─>Cardbus support
In linux kernel since version 2.6.13 (release Date: 2005-08-28)  
Enabled the ETRAX Cardbus driver.

source code:
/arch/cris/arch-v32/drivers/pci/