I'm trying to create my first BSP using a downstream kernel. I have a device that runs some linux where I have root access (and that I can flash), and I have the kernel sources. I created a layer, and when I set it as my `MACHINE` and run bitbake, I get the following error:

```
 TUNE_ARCH is unset. Please ensure your MACHINE configuration includes a valid tune configuration file which will set this correctly.
Error, the PACKAGE_ARCHS variable (all any noarch ${PACKAGE_EXTRA_ARCHS_tune-armv7a} skycontroller3) for DEFAULTTUNE (armv7a) does not contain TUNE_PKGARCH (armv7a).Toolchain tunings invalid:
Tuning 'armv7a' has no defined features, and cannot be used.
```