Manu ("Manufacturing") services are provided by the 010000000000B14A sysmodule, which is installed at the factory but not on normal retail systems.

manu

Cmd	Name	Notes
0		Takes 4 bytes of input, and produces 0 bytes output.
1	FsFile_Exists	Takes an X descriptor, and produces, 8 bytes output.
2		Takes 0x18 bytes of input, a B descriptor, and an X descriptor, and produces 0 bytes of output.
3		Takes 0x18 bytes of input, an A descriptor, and an X descriptor, and produces 0 bytes of output.
4		Takes 4 bytes of input, and produces 0 bytes of output.
5		Takes 0x10 bytes of input and a B descriptor, and produces 8 bytes of output.
6		Takes 0x10 bytes of input and an A descriptor, and produces 8 bytes of output.

This seems to interface with usb:ds. SystemInitializer only uses cmd1..cmd3.

FsFile_Exists

Takes an input path string, returns 8-bytes for the output u8 flag.

Checks whether the specified file exists.

This is "FsFile::Exists" in SystemInitializer.