kickstarts_dir
The option documentation is properly formatted yet
Default: [base_dir]/Kickstarts Example: path/to/dir/with/kickstarts
The following directory is scanned for kickstart ROMs, and kickstart file names are looked up relative to this directory. If you do not specify this path, and do have kickstarts in the default directory, you need to provide the path for a specific kickstart in [kickstart_file].
FS-UAE uses WinUAE’s quickstart code for this, so if you haven’t got exactly the preferred ROM files the automatic configuration will fail. You should use [kickstart_file]/[kickstart_ext_file] instead in this case.
The default is (My) Documents/FS-UAE/Kickstarts
Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/kickstarts_dir