AcpiDump will dump all of the ACPI tables to the same volume the tool is located on. This is sometimes useful, but keep in mind that some UEFI implementations can patch ACPI tables on the way out during ExitBootServices, meaning you might not get the same (correct) data if you dumped tables from the OS proper.
An optional parameter specifies the path, relative to the volume root, where to place the tables. E.g.:
fs16:> AcpiDump.efi
fs16:> AcpiDump.efi MyFunkySystem
The files produced can be loaded by AcpiLoader.