https://www.jianshu.com/p/945168b47487
GRUB_CMDLINE_LINUX="rd.lvm.lv=rhel/swap crashkernel=auto rd.lvm.lv=rhel/root rhgb quiet"
# grub2-mkconfig -o /boot/grub2/grub.cfg
On a system with UEFI firmware, execute the following instead:
# grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg
After finishing the procedure above, the boot loader is reconfigured, and the kernel command-line parameter that you have specified in its configuration file is applied after the next reboot.
To disable CPU power saving states on a Debian Linux system, perform the following procedure: