fails to compile on raspberry pi 4 raspberry os 64 bit

[xevilstar]

root@raspberrypi:/home/pi/Downloads/CH341SER# make make -C /lib/modules/5.4.51-v8+/build M=/home/pi/Downloads/CH341SER make[1]: Entering directory '/root/linux-f2f7e4b23d8788e96f81a7522b2f703e51c53e70' Building modules, stage 2. MODPOST 1 modules ERROR: "_mcount" [/home/pi/Downloads/CH341SER/ch34x.ko] undefined! make[2]: [scripts/Makefile.modpost:94: __modpost] Error 1 make[1]: [Makefile:1622: modules] Error 2 make[1]: Leaving directory '/root/linux-f2f7e4b23d8788e96f81a7522b2f703e51c53e70' make: *** [Makefile:7: default] Error 2 root@raspberrypi:/home/pi/Downloads/CH341SER# uname -a Linux raspberrypi 5.4.51-v8+ #1333 SMP PREEMPT Mon Aug 10 16:58:35 BST 2020 aarch64 GNU/Linux root@raspberrypi:/home/pi/Downloads/CH341SER# gcc --version gcc (Debian 8.3.0-6) 8.3.0 Copyright (C) 2018 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[sirlucjan]

First of all: I compiled and the program is built without problems:

lucjan@archlinux ~/Pobrane/roboczy/roboczy-2/CH341SER $ export LANG=c
lucjan@archlinux ~/Pobrane/roboczy/roboczy-2/CH341SER $ make
make -C /lib/modules/5.8.11.ll27-1-lucjan-git/build  M=/home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER 
make[1]: Entering directory '/usr/lib/modules/5.8.11.ll27-1-lucjan-git/build'
  AR      /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/built-in.a
  CC [M]  /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/ch34x.o
  MODPOST /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/Module.symvers
  CC [M]  /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/ch34x.mod.o
  LD [M]  /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/ch34x.ko
make[1]: Leaving directory '/usr/lib/modules/5.8.11.ll27-1-lucjan-git/build'

Secondly: Why do you compile on your root account? This is highly inadvisable.

Thirdly: Check on another gcc version, you have a bit out of date (the latest of the gcc8 line is 8.4).