kernelconfig_penguin
CONFIG_KERNEL_ABI_CALL0 is not available for the default architecture x86.
Result is shown for architecture xtensa

Call0 ABI

configname: CONFIG_KERNEL_ABI_CALL0

Kernel ABI
└─> Call0 ABI

In linux kernel since version 5.2 (release Date: 2019-07-07)  

Select this option to compile kernel code with call0 ABI even with
toolchain that defaults to windowed ABI.
When this option is not selected the default toolchain ABI will
be used for the kernel code.