Ubuntu server 19.10 rpi4 adafruit python library cannot open /proc/device-tree/compatible

snapcraft
1

I am having all sorts of problems trying to build a snap.

I’m trying to install my snap on an ubuntu server 19.10 running on RPi4 because I ran into issues supporting ALSA in the Raspian OS. I’m now getting different permission errors when running in a different OS.

The application uses several third party libraries. One such library is NeoPixel from Adafruit. The python library is getting an access denied error when trying to open /proc/device-tree/compatible. They also try to open the /proc/device-tree/model and gpio pins.

Is there some sort of document that explains which plug/slot provides which access?

How do I install the pi widget that provides the GPIO pins?

I can’t find any documentation describing how to install one. I tried snap install pi with no success.

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the hardware-observe interface should provide you read access to /proc/device-tree.

1 Like
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Is there a pi gadget for rpi4? I tried installing the channel for rpi3 but get an error about the model not matching.

4

what exactly do you mean by this ? a gadget ? i fear there is none in the store yet …

you could try out my core18 pi4 developer image though …

1 Like
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Pardon the interruption. I thought that the snap core for RPi4 was on hold?
Been using the 19.10.01 server pre-installed image on RPi4 4GB without issues since GA in Nov’19.

Kind regards.

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Ubuntu Core for pi4 is planned for core 20, meanwhile the kernel might get backported to an 18.04 point release which will make an 18.04 server image possible, i dont know what the plans are to have a core18 based pi4 image though, since we can not just replace the kernel with a newer version on existing installs without breaking them (making them unbootable after upgrade) it would have to be a dedicated pi4 image with a dedicated kernel snap just for the pi4. perhaps @sil2100 can elaborate what the exact plan is, since he is doing most/all images nowadays …