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.Cd "options MATH_EMULATE" 42.Cd "options GPL_MATH_EMULATE" 43.\" XXX this is awful hackery to get it to work right... -- cgd 44.\" What the heck does he mean? - cracauer 45.Sh DESCRIPTION 46The 47.Nm npx 48driver enables the use of the system's Numeric Processing Extension 49coprocessor, 50if one is present. Numeric processing extensions are present in 51systems with 52.Sy 486DX 53CPUs and in systems with 54.Sy 387 55or 56.Sy 487SX 57coprocessors. The 58.Nm npx 59driver is required for proper system functioning regardless 60of whether or not a NPX is present. 61.Pp 62If there is no NPX present in the system, the "MATH_EMULATE" or 63"GPL_MATH_EMULATE" option must be defined in the kernel configuration 64file. 65It will provide support for the instructions normally executed by the 66NPX. 67If there is no NPX in the system and the kernel is not built with math 68emulation, the system will not boot. 69.Pp 70For a description of the possible "flags" values see the LINT kernel 71configuration file. 72.Sh CAVEATS 73The emulator is much slower than the NPX coprocessor. 74This will result in poor floating-point math performance 75if the emulator must be used. 76.Pp 77The non-GPL emulator does not support the whole set of npx 78instructions. 79It is sufficient for booting and configuring a system, but it cannot 80support a system with normal workload unless care is taken to compile 81the whole system (including third-party packages) with compiler 82options that avoid the use of the non-emulated instructions. 83.Sh BUGS 84There are lots of them, especially on old cheap motherboards. 85In particular, some motherboards do not have the interrupt lines from 86the NPX to the CPU wired properly. 87If this is the case, the emulator must be used if consistent system 88operation is desired. 89.Pp 90Emulation of the transcendental functions instructions in the non-GPL 91emulator is incorrect. 92Emulation of other instructions is suspect. 93