An error occurs when loading the driver module:

“   Unknown symbol CFG80211_SupBandReInit (err 0)”

After checking the kernel code and the loaded symbol (the command is cat/proc/kallsyms, and the corresponding value is not found), the problem is still not solved

Finally, tentatively check the makefile required during compilation. It is found that the conditional compilation leads to the non compilation of Ko files. Therefore, it is necessary to confirm the following two points:

(1) Function and whether the file where the function is located is conditional compilation. If conditional compilation, whether conditional compilation has been opened

(2) If conditional compilation has been opened, check whether the. O file of the file in makefile is compiled into Ko file