Initial import of Leif's work

docs/grub.texi

@@ -3389,6 +3389,7 @@ you forget a command, you can run the command @command{help}
 * crc::                         Compute or check CRC32 checksums
 * cryptomount::                 Mount a crypto device
 * date::                        Display or set current date and time
+* devicetree::                  Load a device tree blob
 * drivemap::                    Map a drive to another
 * echo::                        Display a line of text
 * export::                      Export an environment variable
@@ -3698,6 +3699,17 @@ hour, minute, and second unchanged.
 @end deffn
 
 
+@node devicetree
+@subsection linux
+
+@deffn Command devicetree file
+Load a device tree blob (.dtb) from a filesystem, for later use by a Linux
+kernel. Does not perform merging with any device tree supplied by firmware,
+but rather replaces it completely.
+@ref{GNU/Linux}.
+@end deffn
+
+
 @node drivemap
 @subsection drivemap