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 section `ld and the H8/300' in Using ld, for a fuller description.
-mh: Generate code for the H8/300H.
-ms: Generate code for the H8/S.
-mint32: Make int data 32 bits by default.
-malign-300: On the h8/300h, use the same alignment rules as for the h8/300. The default for the h8/300h 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.