9.38.1 Options

The following table lists all available s390 specific options:

-m31 | -m64

Select 31- or 64-bit ABI implying a word size of 32- or 64-bit.

These options are only available with the ELF object file format, and require that the necessary BFD support has been included (on a 31-bit platform you must add –enable-64-bit-bfd on the call to the configure script to enable 64-bit usage and use s390x as target platform).

-mesa | -mzarch

Select the architecture mode, either the Enterprise System Architecture (esa) mode or the z/Architecture mode (zarch).

The 64-bit instructions are only available with the z/Architecture mode. The combination of ‘-m64’ and ‘-mesa’ results in a warning message.

-march=CPU

This option specifies the target processor. The following processor names are recognized: g5, g6, z900, z990, z9-109, z9-ec, z10, z196, zEC12, and z13. Assembling an instruction that is not supported on the target processor results in an error message. Do not specify g5 or g6 with ‘-mzarch’.

-mregnames

Allow symbolic names for registers.

-mno-regnames

Do not allow symbolic names for registers.

-mwarn-areg-zero

Warn whenever the operand for a base or index register has been specified but evaluates to zero. This can indicate the misuse of general purpose register 0 as an address register.