Pi5 MESA 7c80: mesaflash can't see the card.

Correct, they are visible under /dev/

Note: Using POSIX non-realtime

Means it's not real time

Cant do this anymore bye all wrote:

Could be. Looks like it could be a self built kernel, there are a couple of options relating to the real time kernel built.

Be interesting to know the origin of the installation. To get the hm2_spix driver I think you still need to build from source as the Rpi packages seem to have a July changelog.
 

FRESH START DEBIAN INSTALL ON 1/3/2025
After cloning  www.linuxcnc.org/iso/rpi-5-debian-bookwo...23-11-17-1520.img.xz to an SD card, then building linuxCNC from source, and Mesflash from source, i am in the following state.
Upon boot after connecting the card:
Mesaflash can not see the card, same invalid cookie error.

After attempting mesaflash, I tried halcmd (loading the same 2 drivers as previously)
halcmd CAN see the card and it's pins.

NOTE: /dev/ only contains "spidev10.0" whereas my other install had "spidev0.0 , spidev0.1 and spidev1"

Thoughts on next steps?

Something is amiss as the kernel is about 11 months newer than the image you linked to.
Now to clear things up.
1: have all your attempts been with the image you linked to.
2: if so what is causing the discrepancy with the kernel build date.

With the previous driver the kernel driver that was loaded on boot was unloaded by the Linuxcnc driver. I’m not entirely sure if it reloaded on exit.

Cant do this anymore bye all wrote:

Something is amiss as the kernel is about 11 months newer than the image you linked to.
Now to clear things up.
1: have all your attempts been with the image you linked to.
2: if so what is causing the discrepancy with the kernel build date.

With the previous driver the kernel driver that was loaded on boot was unloaded by the Linuxcnc driver. I’m not entirely sure if it reloaded on exit.

Everything prior to today, was with the official Raspbian image.

Started with a fresh SD Card for the Debian image linked above today.
Would running system updates have messed with the kernel version?

OK the original attempts were with the official raspbian image. The supplied kernel is not one suitable for Realtime in the way Linuxcnc requires a realtime kernel. There was discussion a few months ago reagrding real time being included in the mainline Linux kernels. When building a real time kernel there are 3 options from memory, if you do not choose the correct type it is not what Linuxcnc expects.
It would depend whether the kernel was pinned (excluded from updates or not) but on further reflection the Raspbian kernel is different to the mainline debian kernel for arm boards.
And honestly when you do an update you should have a look at what is being updated. before proceding.
With the Linuxcnc image did you enable the SPI interfaces in config.txt ?
If you had of clearly stated at the beginning you were using a raspbian image to begin with it would have made life a whole lot easier. It would have been suggested to use the Linuxcnc image from the get go.