RPi4 Mesa install: No 7C81 board found

Thank you for the explanation.
But if this is not possible, I am wondering how people are supposed to use the 7C81?

Because to be very honest I don't care what kind of Linux/Ubuntu version I would need to use, I just would like to get my CNC machine running by using the RPi in combination with a 7C81...
So any advice on how to achieve this is very much appreciated.

I think using Raspberry PI OS is the easiest way
as it look like Debian has poor or completely missing
SPI support on the RPI

PCW wrote:

I think using Raspberry PI OS is the easiest way

But how do I do that?
Because all the installation instructions on the internet are either aimed towards the plug-and-play file from the LinuxCNC frontpage (but this file is not compatible with RPi's that have been manufactured in the past 2 years), or they follow the instructions from Rodw (like I did yesterday but apparantly isn't working):
github.com/rodw-au/linuxcnc/blob/rodw-ge...etting-linuxcnc.adoc

I just installed Raspberry Pi OS with the Raspberry Pi Imager tool.
But I don't know how to proceed from there, as for example the commands below are not recognized:
 

Hey Stef, you can try these images

github.com/Expatria-Technologies/remora-flexi-hal/releases

www.forum.linuxcnc.org/9-installing-linu...cnc?start=150#253623

They will be plug and play.
The official lcnc rpi image does support spi, ive used it before with mesaflash

edit, stef, do not worry. I have several 7C81 boards. If it were not for the RPI image mismatch, everything wuld be good. The linuxcnc rpi images are surprisingly turn-key, just the official one has fallen to the wayside. I havent tried the expatria one with a mesa, but I am using elvalvo's RPI images and 7c81 with very much success.

I have connected pi 4(powered by PI OS) with Mesa7c81 using idc26 cable and followed the instructions given in the following video
BUT when i write the command sudo mesaflash --device 7c81 --addr /dev/spidev0.0 --spi --fix-boot-block --wirte 7c81_5abobx3d.bit
I get the following error Unable to set bpw32 , falllback to bpw8
Unexpected cookie at 0100..0110:
00000000 00000000 00000000
No 7c81 board found
NOTE: i have already checked that spi communication is working using the ls /dev/spidev* command
Do you know how to correct this error? Your valuable suggestion will be highly appreciated.

It's probably a bad idea to run commands that write to 7C81 flash without
a fully tested interface (If the --readhmid mesaflash command does not work
100% reliably, I would  not try any write commands or especially write-boot-block
commands)

Does the 7C81 FPGA configuration load at power up (no red LEDs after power-on)?

How long is the 40 pin cable? It may be a cable length or wiring error.

i had also tried the --readhmid command but It gives me the same error . There is an orange indication light on the mesa board after I power it up using the IDC26 cable which is not longer than 2.5 inches as mentioned in the manual. Note : No red leds after powering on the mesa board.

Not sure, could possible be a bad cable.