default or selected kernelversion does not have config value CONFIG_SERIAL_M32R_SIO.
Result is shown for kernelversion 6.7-rc3
M32R SIO I/F
modulename: m32r_sio.ko
configname: CONFIG_SERIAL_M32R_SIO
Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>M32R SIO I/F
In linux kernel since version 2.6.20 (release Date: 2007-02-04)
Say Y here if you want to use the M32R serial controller.