+The following options are available when as is configured for the s390
+processor family.
+.IP "\fB\-m31\fR" 4
+.IX Item "-m31"
+.PD 0
+.IP "\fB\-m64\fR" 4
+.IX Item "-m64"
+.PD
+Select the word size, either 31/32 bits or 64 bits.
+.IP "\fB\-mesa\fR" 4
+.IX Item "-mesa"
+.PD 0
+.IP "\fB\-mzarch\fR" 4
+.IX Item "-mzarch"
+.PD
+Select the architecture mode, either the Enterprise System
+Architecture (esa) or the z/Architecture mode (zarch).
+.IP "\fB\-march=\fR\fIprocessor\fR" 4
+.IX Item "-march=processor"
+Specify which s390 processor variant is the target, \fBg6\fR, \fBg6\fR,
+\&\fBz900\fR, \fBz990\fR, \fBz9\-109\fR, \fBz9\-ec\fR, or \fBz10\fR.
+.IP "\fB\-mregnames\fR" 4
+.IX Item "-mregnames"
+.PD 0
+.IP "\fB\-mno\-regnames\fR" 4
+.IX Item "-mno-regnames"
+.PD
+Allow or disallow symbolic names for registers.
+.IP "\fB\-mwarn\-areg\-zero\fR" 4
+.IX Item "-mwarn-areg-zero"
+Warn whenever the operand for a base or index register has been specified
+but evaluates to zero.
+.PP