disable hyper-threading in linux, SMT

• on boot:
• add kernel options : maxcpus=N(# of physical core) 
• How:
  with sudo (root) privileges open /etc/default/grub with your favorite text editor.
  Find the line that begins with GRUB_CMDLINE_LINUX_DEFAULT=
  https://askubuntu.com/questions/942728/disable-hyper-threading-in-ubuntu/942843#942843  
• grub-mkconfig -o /boot/grub/grub.cfg 
• systemd boot:
• /boot/loader/entries/ArchLabs.conf
• after boot: reference