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Porting to a new device/Miscellaneous tips

From postmarketOS Wiki

During initramfs generation: "modprobe: WARNING: Module drm not found in directory /lib/modules/..."

This means, that a module can not be put in an initramfs. When you are not using a mainline kernel, it is likely that there are no modules configured, but the code is built directly into the kernel. This means, it is expected and can be ignored.

The screen doesn't get updated

There is a known bug where if you execute cat /sys/class/graphics/fb0/modes > /sys/class/graphics/fb0/mode exactly one frame is drawn, and the screen isn't updated otherwise.

If that is the case, add msm-fb-refresher to device package's depends.

Device reboots

  • If your device always reboots after the same time (e.g. 2 minutes) after booting, you probably need to feed (or disable) a watchdog. Try to search your kernel config for watchdog, and also the internet for watchdog + your phone name.
  • Android: The kernel config option CONFIG_ANDROID_LOW_MEMORY_KILLER may cause reboots. Please check if you have disabled it. If this helps you, please let us know, so we can consider checking for this option.
  • Android: it is possible to get the dmesg log from just before the crash after the reboot if you enable some kernel options.

SSH / udev / touch screen doesn't work

  • Make sure that DEVTMPFS is enabled in your kernel config. Do not enable DEVTMPFS_MOUNT.

I can't access the framebuffer device