2 .\" Copyright (c) 1993 Christopher G. Demetriou
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
6 .\" modification, are permitted provided that the following conditions
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 without specific prior written permission
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.
30 .\" from: npx.4,v 1.1 1993/08/06 10:58:03 cgd Exp
31 .\" $FreeBSD: src/share/man/man4/man4.i386/npx.4,v 1.9.2.3 2001/08/17 13:08:46 ru Exp $
32 .\" $DragonFly: src/share/man/man4/man4.i386/npx.4,v 1.3 2007/12/25 12:40:32 swildner Exp $
39 .Nd Numeric Processing Extension coprocessor and emulator
41 .Cd "device npx0 at nexus? port IO_NPX flags 0x0 irq 13"
43 For hosts without a FPU coprocessor add:
44 .Cd "options MATH_EMULATE"
48 driver enables the use of the system's Numeric Processing Extension
49 coprocessor, if one is present.
50 Numeric processing extensions are present in systems with
52 CPUs and in systems with
57 driver is required for proper system functioning regardless
58 of whether or not a NPX is present.
60 If there is no NPX present in the system, the
62 option must be defined in the kernel configuration file.
63 It will provide support for the instructions normally executed by the NPX.
64 If there is no NPX in the system and the kernel is not built with math
65 emulation, the system will not boot.
69 kernel configuration uses the
73 For a description of the possible "flags" values see the LINT kernel
76 The emulator is much slower than the NPX coprocessor.
77 This will result in poor floating-point math performance
78 if the emulator must be used.
80 The emulator does not support the whole set of npx instructions.
81 It is sufficient for booting and configuring a system, but it cannot
82 support a system with normal workload unless care is taken to compile
83 the whole system (including third-party packages) with compiler
84 options that avoid the use of the non-emulated instructions.
86 There are lots of them, especially on old cheap motherboards.
87 In particular, some motherboards do not have the interrupt lines from
88 the NPX to the CPU wired properly.
89 If this is the case, the emulator must be used if consistent system
94 option, transcendental function instructions are not implemented.
95 Emulation of other instructions is suspect.