Clarify potential drawback of previous change.
[emacs.git] / src / m / intel386.h
blob44ba3245b2e8a40748b6897b78cc534d3dbd2c42
1 /* Machine description file for intel 386.
2 Copyright (C) 1987, 2001, 2002, 2003, 2004, 2005,
3 2006, 2007 Free Software Foundation, Inc.
5 This file is part of GNU Emacs.
7 GNU Emacs is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
10 any later version.
12 GNU Emacs is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU Emacs; see the file COPYING. If not, write to
19 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
23 /* The following line tells the configuration script what sort of
24 operating system this machine is likely to run.
25 USUAL-OPSYS="note"
27 NOTE-START
28 Intel 386 (-machine=intel386 or -machine=is386.h)
30 The possibilities for -opsystem are: bsd4-2, usg5-2-2, usg5-3,
31 isc2-2, 386-ix, esix, linux, sco3.2v4, and xenix.
33 18.58 should support a wide variety of operating systems.
34 Use isc2-2 for Interactive 386/ix version 2.2.
35 Use 386ix for prior versions.
36 Use esix for Esix.
37 Use linux for Linux.
38 It isn't clear what to do on an SCO system.
40 -machine=is386 is used for an Integrated Solutions 386 machine.
41 It may also be correct for Microport systems.
43 Cubix QBx/386 (-machine=intel386 -opsystem=usg5-3)
45 Changes merged in 19.1. Systems before 2/A/0 may fail to compile etags.c
46 due to a compiler bug.
48 Prime EXL (-machine=intel386 -opsystem=usg5-3)
50 Minor changes merged in 19.1.
51 NOTE-END */
53 /* Define WORDS_BIG_ENDIAN iff lowest-numbered byte in a word
54 is the most significant byte. */
56 #undef WORDS_BIG_ENDIAN
58 /* Define NO_ARG_ARRAY if you cannot take the address of the first of a
59 * group of arguments and treat it as an array of the arguments. */
61 /* #define NO_ARG_ARRAY */
63 /* Define WORD_MACHINE if addresses and such have
64 * to be corrected before they can be used as byte counts. */
66 /* #define WORD_MACHINE */
68 /* Now define a symbol for the cpu type, if your compiler
69 does not define it automatically:
70 Ones defined so far include vax, m68000, ns16000, pyramid,
71 orion, tahoe, APOLLO and many others */
73 #define INTEL386
75 /* Use type int rather than a union, to represent Lisp_Object */
77 #define NO_UNION_TYPE
79 /* crt0.c, if it is used, should use the i386-bsd style of entry.
80 with no extra dummy args. On USG and XENIX,
81 NO_REMAP says this isn't used. */
83 #define CRT0_DUMMIES bogus_fp,
85 /* crt0.c should define a symbol `start' and do .globl with a dot. */
87 #define DOT_GLOBAL_START
89 #ifdef XENIX
90 /* Data type of load average, as read out of kmem. */
91 #define LOAD_AVE_TYPE short
93 /* Convert that into an integer that is 100 for a load average of 1.0 */
94 #define LOAD_AVE_CVT(x) (((double) (x)) * 100.0 / FSCALE)
96 #define FSCALE 256.0 /* determined by experimentation... */
97 #endif
100 #ifdef SOLARIS2
101 /* Data type of load average, as read out of kmem. */
102 #define LOAD_AVE_TYPE long
104 /* Convert that into an integer that is 100 for a load average of 1.0 */
105 /* This is totally uncalibrated. */
106 #define LOAD_AVE_CVT(x) ((int) (((double) (x)) * 100.0 / FSCALE))
108 /* J.W.Hawtin@lut.ac.uk say Solaris 2.4 as well as Solaris 2.1 on X86
109 requires -lkvm as well.
110 And handa@etl.gov.jp says that -lkvm needs -llelf, at least on 2.5. */
111 #define LIBS_MACHINE -lkvm -lelf
113 #ifndef SOLARIS2_4
114 /* J.W.hawtin@lut.ac.uk says Solaris 2.1 on the X86 has FSCALE defined in a
115 system header. */
116 #else /* SOLARIS2_4 */
117 #ifndef __GNUC__
118 #if 0 /* wisner@gryphon.com says this screws up cpp */
119 #define C_SWITCH_MACHINE -Xa
120 #endif
121 #endif /* not __GNUC__ */
122 #endif /* SOLARIS2_4 */
124 /* configure thinks solaris X86 has gethostname, but it does not work,
125 so undefine it. */
126 #undef HAVE_GETHOSTNAME
128 #else /* not SOLARIS2 */
129 #ifdef USG5_4 /* Older USG systems do not support the load average. */
130 /* Data type of load average, as read out of kmem. */
132 #define LOAD_AVE_TYPE long
134 /* Convert that into an integer that is 100 for a load average of 1.0 */
135 /* This is totally uncalibrated. */
137 #define LOAD_AVE_CVT(x) ((int) (((double) (x)) * 100.0 / FSCALE))
138 #define FSCALE 256.0
139 #endif
140 #endif /* not SOLARIS2 */
142 /* Define CANNOT_DUMP on machines where unexec does not work.
143 Then the function dump-emacs will not be defined
144 and temacs will do (load "loadup") automatically unless told otherwise. */
146 /* #define CANNOT_DUMP */
148 /* Define VIRT_ADDR_VARIES if the virtual addresses of
149 pure and impure space as loaded can vary, and even their
150 relative order cannot be relied on.
152 Otherwise Emacs assumes that text space precedes data space,
153 numerically. */
155 /* #define VIRT_ADDR_VARIES */
157 #ifdef XENIX
158 /* Define NO_REMAP if memory segmentation makes it not work well
159 to change the boundary between the text section and data section
160 when Emacs is dumped. If you define this, the preloaded Lisp
161 code will not be sharable; but that's better than failing completely. */
163 #define NO_REMAP
165 /* Since cannot purify, use standard Xenix 386 startup code. */
167 #define START_FILES /lib/386/Sseg.o pre-crt0.o /lib/386/Scrt0.o
169 /* These really use terminfo. */
171 #define LIBS_TERMCAP /lib/386/Slibcurses.a \
172 /lib/386/Slibtinfo.a /lib/386/Slibx.a
174 /* Standard libraries for this machine. Since `-l' doesn't work in `ld'. */
175 /* '__fltused' is unresolved w/o Slibcfp.a */
176 #define LIB_STANDARD /lib/386/Slibcfp.a /lib/386/Slibc.a
177 #else /* not XENIX */
179 /* this brings in alloca() if we're using cc */
180 #ifdef USG
181 #ifndef LIB_STANDARD
182 #ifdef USG5_4
183 #define LIB_STANDARD -lc
184 #else /* not USG5_4 */
185 #define LIB_STANDARD -lPW -lc
186 #endif /* not USG5_4 */
187 #endif /* LIB_STANDARD */
189 #define NO_REMAP
190 #define TEXT_START 0
191 #endif /* USG */
192 #endif /* not XENIX */
194 #ifdef USG5_4
195 #define DATA_SEG_BITS 0x08000000
196 #endif
198 #ifdef MSDOS
199 #define NO_REMAP
200 #endif
202 #ifdef WINDOWSNT
203 #define VIRT_ADDR_VARIES
204 #define DATA_END get_data_end ()
205 #define DATA_START get_data_start ()
206 #define NO_ARG_ARRAY
207 #endif
209 #ifdef linux
210 /* libc-linux/sysdeps/linux/i386/ulimit.c says that due to shared library, */
211 /* we cannot get the maximum address for brk */
212 #define ULIMIT_BREAK_VALUE (32*1024*1024)
214 #define SEGMENT_MASK ((SEGMENT_SIZE)-1)
215 #endif
217 /* arch-tag: 746338f0-cb7b-4f49-a98c-cb50817cf2ec
218 (do not change this comment) */