The Nim for embedded systems section of the compiler user guide is unclear.
Settings such as nimPage256 and nimMemAlignTiny are mentioned, but it does not say how or where to set these.
Is it done with command line switches, in the config files or within the .nim file to be compiled?
They’re just like other compiler settings. You can pass them as arguments in when you run the compiler. They should be prefixed with the “defines” like nim c -d:nimPage256 … for example.
Generally it’s better to put them in a config.nims file.