CONFIG_IP_CHECKSUM_L1 is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_IP_CHECKSUM_L1.
Result is shown for kernelversion 6.5.1

Locate IP Checksum function in L1 Memory

configname: CONFIG_IP_CHECKSUM_L1

Linux Kernel Configuration
└─>Blackfin Processor Options
└─>Blackfin Kernel Optimizations
└─>Locate IP Checksum function in L1 Memory
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
If enabled, the IP Checksum function is linked
into L1 instruction memory. (less latency)

depends
NOT CONFIG_SMP