7i76D TB3 power?

You've missed a step. Tommy's instructions are not very clear about how to make the new kernel the default..

Open synaptic:
Search for grub-customizer and mark it for installation
If it is not found, go to settings/repositories and add a new repository
Paste this into the URI: ppa:danielrichter2007/grub-customizer
Click on apply, search for grub-customizer and mark it for installation. Close Synaptic once complete
Go to the menu and select settings/grub customizer
On the list configuration tab. Click on Debian/GNU/Linux with Linux 5.10.0-8-rt-amd64
Click on the up arrow until it's the very first entry
Check on the General Settings tab ensure that default entry is predefined and ther(first entry) is selected
Click on save and close.
Restart your machine to boot into the PREEMPT_RT kernel
Open a terminal and type uname -v and check it reports PREMPT_RT

Yes, I'm pretty sure that's what happened, Rod. I'd come to the same conclusion last night. After installing Mint 20 and LinuxCNC 2.8.2, I used Grub Customiser to move "Ubuntu" from the bottom of the list to the top, as "Ubuntu" was the only boot menu item that seemed to work, after trying a few of them. Grub Customiser seems to be one of those programs that is documented by the author(s) - it makes sense to them and perhaps doesn't contain any factual errors but for a newcomer, it's really not clear what you are looking at.

Here's what I've got, with the "Ubuntu" line renamed back to its original name. I'm pretty sure it was originally the very bottom line by itself before I moved it to the very top.

I'm guessing that some of the indented lines need to be in the correct relative position. I can't see a "Debian/GNU/Linux with Linux 5.10.0-8-rt-amd64", although there is a 4.9.0-13-rt-amd64.

Do I need to try to put it back to how it was or is there a line(s) missing, do you think? I feel some coverage of this in the Grub Customiser documentation might have been helpful, although it's quite possible I simply missed it of course.

 

Sounds as if we are homing in on the issue. I'm out of my depth here but hoping someone can tell me how to correct the Grub config. Hopefully it's a relatively simple matter of rearranging a few of the lines?

I did that exactly as you said and it seems to have started the RT process. However, it's not happy trying to call hm2_pci

Debug file information:
Note: Using POSIX realtime
hm2/hm2_5i25.0: hm2_sserial_waitfor: Timeout (1007mS) waiting for addr 4b00 &mask ffffffff val ffffefff
hm2/hm2_5i25.0: DATA addr 4c00 after timeout: ffffefff
hm2/hm2_5i25.0: failed to parse Module Descriptor 5
hm2_5i25.0: board fails HM2 registration
RTAPI_PCI: Unmapped 65536 bytes at 0x7f30db731000
Driver probe function failed!
hm2_pci: error registering PCI driver
hm2_pci: rtapi_app_main: Operation not permitted (-1)
./hallib/Bantam_v1.hal:9: waitpid failed /usr/bin/rtapi_app hm2_pci

./hallib/Bantam_v1.hal:9: /usr/bin/rtapi_app exited without becoming ready
./hallib/Bantam_v1.hal:9: insmod for hm2_pci failed, returned -1
4565
Stopping realtime threads
Unloading hal components
Note: Using POSIX realtime

 

I wonder if I screwed something else up?

Note I have 5i25 and 7i76D / 7i85

mesaflash: command not found