.\" .\" Copyright (c) 1993 Christopher G. Demetriou .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by Christopher G. Demetriou. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software withough specific prior written permission .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" from: npx.4,v 1.1 1993/08/06 10:58:03 cgd Exp .\" $FreeBSD: src/share/man/man4/man4.i386/npx.4,v 1.9.2.3 2001/08/17 13:08:46 ru Exp $ .\" $DragonFly: src/share/man/man4/man4.i386/npx.4,v 1.2 2003/06/17 04:36:59 dillon Exp $ .\" .Dd August 28, 1993 .Dt NPX 4 i386 .Os .Sh NAME .Nm npx .Nd Numeric Processing Extension coprocessor and emulator .Sh SYNOPSIS .Cd "device npx0 at nexus? port IO_NPX flags 0x0 irq 13" .Pp For hosts without a FPU coprocessor add: .Cd "options MATH_EMULATE" or .Cd "options GPL_MATH_EMULATE" .\" XXX this is awful hackery to get it to work right... -- cgd .\" What the heck does he mean? - cracauer .Sh DESCRIPTION The .Nm driver enables the use of the system's Numeric Processing Extension coprocessor, if one is present. Numeric processing extensions are present in systems with .Sy 486DX CPUs and in systems with .Sy 387 or .Sy 487SX coprocessors. The .Nm driver is required for proper system functioning regardless of whether or not a NPX is present. .Pp If there is no NPX present in the system, the MATH_EMULATE or GPL_MATH_EMULATE option 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. .Pp You can choose to use a much more fully-featured math emulator (under the GPL license) by including the option GPL_MATH_EMULATE in your kernel configuration file instead of the MATH_EMULATE option. .Pp The .Sy GENERIC kernel configuration uses the MATH_EMULATE option. .Pp For a description of the possible "flags" values see the LINT kernel configuration file. .Sh CAVEATS The emulator is much slower than the NPX coprocessor. This will result in poor floating-point math performance if the emulator must be used. .Pp The non-GPL emulator does not support the whole set of npx instructions. It is sufficient for booting and configuring a system, but it cannot support a system with normal workload unless care is taken to compile the whole system (including third-party packages) with compiler options that avoid the use of the non-emulated instructions. .Sh BUGS There are lots of them, especially on old 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. .Pp When using the default MATH_EMULATE option, transcendental function instructions are not implemented. Emulation of other instructions is suspect.