default or selected kernelversion does not have config value CONFIG_IBM_NEW_EMAC_RX_COPY_THRESHOLD.
Result is shown for kernelversion 6.2.5

RX skb copy threshold (bytes)

configname: CONFIG_IBM_NEW_EMAC_RX_COPY_THRESHOLD

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet (10 or 100Mbit)
└─>RX skb copy threshold (bytes)
In linux kernel since version 2.6.24 (release Date: 2008-01-24)