Why Fatdog does not use my savefile?

Usually there are two reasons for that.
  1. Fatdog cannot find the device on which the savefile is located.
  2. Fatdog cannot find the savefile itself.

Problem #1 usually happens if the savefile is located in a "slow" device, like USB flash drive. In this case, Fatdog boots too fast that when the device is finally ready for use, Fatdog has already completed its boot process and missed the device altogether.

The solution to this is simple, use the waitdev=n boot parameter to slow down Fatdog and tell it to wait a number of n seconds before continuing. Usually 3 or 5 seconds is enough for most devices. Slower devices may need more.

Problem #2 usually happens if you rename the savefile and/or put the savefile in a sub-directory, when you created the savefile. It is important to know that by default, Fatdog only scans for savefiles in root directory of devices, and then only look for the default filename of the savefile (without the extension).

The default filename is fd64save.ext4, which means that Fatdog will only find savefiles named as fd64save.ext4, fd64save.3fs, fd64save-old.ext2, fd64save-backup.sfs, etc if they are located in the root directory.

It is possible to tell Fatdog to search deeper into sub-directories using the search boot parameter, but this is not recommended as searching is slow. The better way is, to tell Fatdog exactly where your savefile is and what is the name, using savefile boot parameter. Doing this stops Fatdog from doing any search at all, instead it will use the given device and given directory and given filename as its savefile (if this fails, it will simply boot without a savefile).