/usr/src/linux-source-3.13.0/debian.master/d-i/firmware/README.txt is in linux-source-3.13.0 3.13.0-100.147.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | #
# Place the names of udeb modules into this directory that require
# runtime firmware.
#
|