Boot Options

Standard Options

The following needs to be added to the end of /boot/cmdline.txt

• processor.max_cstate=1
  This limits the CPU to a C1 state (prevents it from sleeping)
  https://gist.github.com/Brainiarc7/8dfd6bb189b8e6769bb5817421aec6d1
• isolcpus=2,3
  This prevents the linux kernel from scheduling normal tasks to the last two processors.

The userspace part of linuxcnc uses a special realtime API that makes use of the processor cores that have been isolated.
In this case we have a 4 core system, we leave the first two for the operating system and then use the last two for linuxcnc

• fsck.repair=yes
  If fsck prompts to repair something, provide yes as the answer
  This helps with making sure the operating system doesn't stall on bootup.
  It just tries to fix the filesystem automatically if there's a problem without asking.