default or selected kernelversion does not have config value CONFIG_USB_GADGET_LEGACY.
Result is shown for kernelversion 5.10.152
Legacy USB Gadget Support
configname: CONFIG_USB_GADGET_LEGACY
Linux Kernel Configuration
└─>Device Drivers
└─>USB support
└─>USB Gadget Support
└─>Legacy USB Gadget Support
In linux kernel since version 4.15.1 (release Date: 2018-02-03)
Legacy USB gadgets are USB gadgets that do not use the USB gadget
configfs interface.
configfs interface.