These -m options are defined for the H8/300 implementations:
-mrelax
Shorten some address references at link time, when possible; uses the
linker option -relax. See H8/300 Options - Using the GNU Compiler Collection (GCC), for a fuller description.
-mh
Generate code for the H8/300H.
-ms
Generate code for the H8S.
-mn
Generate code for the H8S and H8/300H in the normal mode. This switch
must be used either with -mh or -ms.
-ms2600
Generate code for the H8S/2600. This switch must be used with -ms.
-mint32
Make int data 32 bits by default.
-malign-300
On the H8/300H and H8S, use the same alignment rules as for the H8/300. The default for the H8/300H and H8S is to align longs and floats on 4 byte boundaries. -malign-300 causes them to be aligned on 2 byte boundaries. This option has no effect on the H8/300.