when building for the rpi3 target - how much memory is allocated to the GPU - i normally run with 16MB (as its the minimum you can set in raspi-config) to free up as much memory as possible and i run them the headless and no need for a gui.
Is this possible or is it already the default? Reading through the docs and a search does not give me any answers
When overriding either of these files, you need to copy the original one from the system you are using, because the override will replace the original, not merge with it. You can download these files from GitHub and then add them to your project.
When I experiment with the config.txt settings, I usually put the MicroSD card into my laptop and modify the file directly. When I have something that boots, then I update the fwup.conf.
My only guess is that 16 MB is too small for the “X” version of the Raspberry Pi’s VideoCore firmware. The Pi has several firmware images. See here: https://github.com/raspberrypi/firmware/tree/master/boot. The “_x” one is the most capable. The “_cd” one is the smallest and most limited, I believe. Everything is relative, but in my opinion, we enable a ton on our Raspberry Pi systems since this area tends to be harder to people to debug and for us to support. To select the other firmware images, I’d probably download them from the github link above and manually copy them over to the boot partition to make sure that your configuration boots. After you’re happy with that, it’s a Buildroot configuration option to select the Raspberry Pi firmware. If you going to be modifying Buildroot options, you might as well disable rpi-userland, alsalib and espeak and shrink your firmware by maybe 1/3rd.
Could you try running cat "/boot/config.txt" at the IEx prompt on the Raspberry Pi 3. The boot partition gets mounted read-only to there.
Another option is to plug the MicroSD card into your computer, mount the boot partition, and open the config.txt in your editor.
After you check that out, you’ll almost certainly need to modify the Nerves system to include the WiFi drivers and firmware for your external WiFi adapter. I’d have to double check, but I’m pretty sure that only the internal Broadcom WiFi drivers are included the official Nerves systems for Raspberry Pi’s with built-in WiFi.
You are spot on … this is where I left off the other night. I was trying to use mix nerves.system.shell to get a shell booted up to reconfigure the kernel but was running into a bug w/ the docker invocation.
So turns out my stuff was actually working correctly. The issue was that the disable-wifi.dtbo file did not exist on my device. Once I was able to do that by adding the correct lines to my fwup.conf. Here is a diff between my file and the factory rpi4 one: