NAME    [Toc]    [Back]

     npx - Numeric Processing Extension coprocessor and emulator

SYNOPSIS    [Toc]    [Back]

     option GPL_MATH_EMULATE
     npx0 at isa? port "IO_NPX0" irq 13

DESCRIPTION    [Toc]    [Back]

     The npx driver enables the use of the system's Numeric  Processing Extension
 coprocessor, if one is present.  Numeric processing extensions are
     present in systems with 486DX CPUs and in systems  with  387
or 487SX coprocessors.
   The  npx  driver is required for proper system
functioning regardless
 of whether or not a NPX is present.

     If  there  is  no  NPX  present   in   the   system   option
GPL_MATH_EMULATE must be
     defined  in  the kernel configuration file.  It will provide
support for
     the instructions normally executed by the NPX.  If there  is
no NPX in the
     system  and the kernel is not built with math emulation, the
system will
     not boot.

SEE ALSO    [Toc]    [Back]

     intro(4), isa(4)

CAVEATS    [Toc]    [Back]

     The emulator is much slower than the NPX coprocessor.   This
will result
     in poor floating-point math performance if the emulator must
be used.

BUGS    [Toc]    [Back]

     There are lots of them, especially  on  cheap  motherboards.
In particular,
     some  motherboards  do not have the interrupt lines from the
NPX to the CPU
     wired properly.  If this is the case, the emulator  must  be
used if consistent
 system operation is desired.

     Emulation  of  the  transcendental functions instructions is
incorrect.  Emulation
 of other instructions is suspect.

OpenBSD     3.6                          August      6,      1993