Downgrading from 2.9 to 2.8.4 stretch

Hey. I've been running 2.9 for a while, pre0 release on debian stretch. I've been encountering some issue so went to upgrade to master but seems to be buster only now. I probably shouldn't have made the jump so early but anyway. Is it feasible to downgrade to 2.8.4 now that a version is there for mesa 7i96? Or would you suggest a fresh install. I had a wee search but couldn't find anything. I guess noone is as daft as me to run their two machines on an early dev version. (Not complaining, just curious).

Related, are there any key issues with differences in hal and ini between the two? I understand 2.8 has joints etc like 2.9 (im using dual synchronised ballscrews and "squaring" on y) 

There should be no config differences between 2.9 and 2.8.x

You should be able to just force the version to 2.8.4 in the Synaptic package manager. There are 2.8.4 packages for Stretch.

(edit) You might also have to change the repository settings to point at the 2.8 version. This will be the same instructions in that respect to updating 2.7 to 2.8:
linuxcnc.org/docs/stable/html/getting-st..._setting_apt_sources
Just follow steps 1.1 and 1.2
 

Another way is uninstall LCNC and use RIP installation.
linuxcnc.org/docs/2.9/html/code/building-linuxcnc.html

It is not easy, but you can install several versions LCNC.

Thanks gents. Im trying an install of 2.9 on another drive with 5.10 rt kernel. Will see how it does. Good to know the config didn't change from 2.8 to 2.9. I remember 2.7 to 2.8 was a big change due to joints etc. Im not sure how well my machine will do with debian 11 but, since 2.9 isn't maintained for stretch due to python 2 I guess its good to change. Otherwise its back to 2.8.4 on stretch I guess. Appreciate the info. J

I may try the RIP actually, thanks. Ill see how the latency is on 11 and go from there. Im currently building from git based on gnipsels instructions (for first time) so we'll see how that goes too

I wanted to ask why are you trying Debian 11? I know there are a lot of people here trying different Linux distributions, but I've always wondered what makes them do it.

I've been having some issues with my 2.9 system with read errors to the 7i96 (in another thread) i actually have two machines with 7i96 both are producing the same issue. I've replaced the NIC with an intel and have the same issue and have a strong feeling it is machine(PC) related/config. Id be more than happy to stay with stretch (i have another machine running an old ubuntu install and im in no rush to update it) but since 2.9 is not available on stretch I have to either go up to 10/11 to install 2.9 or stick with stretch and downgrade to 2.8.4. If that makes sense. Im very much happy with any version of Linux that works reliably. My ubuntu box hasn't been updated since and never skips a beat so it'll be like that till it dies I guess. I need 2.8 plus to support dual y axis and the 7i96 too so choices are a bit more limited. Also v 11 is known to be more stable kernel wise for the NIC as far as I'm aware so that is why is skipped 10. I was trying also to stay with 2.9 so I don't have to worry much about config changes (if any) since it has two machine configs on there.