The following section describes command-line options specific to UNIX ABI, for restricting the floating-point register range, and defining the kernel mode calling convention. They must be used in conjuction with the -F ELF64 option.
-M rfp |
IAS restricts floating-point registers to
the range F6 - F11.
This results in less register saves and restores when entering and exiting
the kernel, thereby reducing system time. Attempts to use other floating-point
registers cause an error. |
-M const_gp |
IAS sets the single global pointer (GP) model
in the object file. The kernel is then considered a single model, with
one GP. |
-M no_plabel |
IAS sets the model in the object file to single
GP and no function descriptors (plabels). As with the -M const_gp option, the kernel is then considered
a single GP and doesn’t use plabels. |