1.\" 2.\" Copyright (c) 1993 Christopher G. Demetriou 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. All advertising materials mentioning features or use of this software 14.\" must display the following acknowledgement: 15.\" This product includes software developed by Christopher G. Demetriou. 16.\" 3. The name of the author may not be used to endorse or promote products 17.\" derived from this software withough specific prior written permission 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" from: npx.4,v 1.1 1993/08/06 10:58:03 cgd Exp 31.\" $FreeBSD$ 32.\" 33.Dd August 28, 1993 34.Dt NPX 4 i386 35.Os FreeBSD 36.Sh NAME 37.Nm npx 38.Nd Numeric Processing Extension coprocessor and emulator 39.Sh SYNOPSIS 40.Cd "device npx0 at nexus? port IO_NPX flags 0x0 irq 13" 41.Pp 42For hosts without a FPU coprocessor add: 43.Cd "options MATH_EMULATE" 44or 45.Cd "options GPL_MATH_EMULATE" 46.\" XXX this is awful hackery to get it to work right... -- cgd 47.\" What the heck does he mean? - cracauer 48.Sh DESCRIPTION 49The 50.Nm npx 51driver enables the use of the system's Numeric Processing Extension 52coprocessor, 53if one is present. Numeric processing extensions are present in 54systems with 55.Sy 486DX 56CPUs and in systems with 57.Sy 387 58or 59.Sy 487SX 60coprocessors. The 61.Nm npx 62driver is required for proper system functioning regardless 63of whether or not a NPX is present. 64.Pp 65If there is no NPX present in the system, the MATH_EMULATE or 66GPL_MATH_EMULATE option must be defined in the kernel configuration 67file. 68It will provide support for the instructions normally executed by the 69NPX. 70If there is no NPX in the system and the kernel is not built with math 71emulation, the system will not boot. 72.Pp 73You can choose to use a much more fully-featured math emulator (under the 74GPL license) by including the option GPL_MATH_EMULATE in your kernel 75configuration file instead of the MATH_EMULATE option. 76.Pp 77The 78.Sy GENERIC 79kernel configuration uses the MATH_EMULATE option. 80.Pp 81For a description of the possible "flags" values see the LINT kernel 82configuration file. 83.Sh CAVEATS 84The emulator is much slower than the NPX coprocessor. 85This will result in poor floating-point math performance 86if the emulator must be used. 87.Pp 88The non-GPL emulator does not support the whole set of npx 89instructions. 90It is sufficient for booting and configuring a system, but it cannot 91support a system with normal workload unless care is taken to compile 92the whole system (including third-party packages) with compiler 93options that avoid the use of the non-emulated instructions. 94.Sh BUGS 95There are lots of them, especially on old cheap motherboards. 96In particular, some motherboards do not have the interrupt lines from 97the NPX to the CPU wired properly. 98If this is the case, the emulator must be used if consistent system 99operation is desired. 100.Pp 101When using the default MATH_EMULATE option, 102transcendental function instructions are not implemented. 103Emulation of other instructions is suspect. 104