@emph{S/390 and zSeries Options}
@gccoptlist{
--mcpu=@var{cpu-type} -march=@var{cpu-type} @gol
+-mtune=@var{cpu-type} -march=@var{cpu-type} @gol
-mhard-float -msoft-float -mbackchain -mno-backchain @gol
-msmall-exec -mno-small-exec -mmvcle -mno-mvcle @gol
-m64 -m31 -mdebug -mno-debug -mesa -mzarch}
representing a certain processor type. Possible values for
@var{cpu-type} are @samp{g5}, @samp{g6} and @samp{z900}.
-@item -mcpu=@var{arch}
-@opindex mcpu
+@item -mtune=@var{arch}
+@opindex mtune
Tune to @var{cpu-type} everything applicable about the generated code,
except for the ABI and the set of available instructions.
The list of @var{arch} values is the same as for @option{-march}.