1 ;;;; tags which are set during the build process and which end up in
2 ;;;; CL:*FEATURES* in the target SBCL, plus some comments about other
3 ;;;; CL:*FEATURES* tags which have special meaning to SBCL or which
4 ;;;; have a special conventional meaning
6 ;;;; Note that the recommended way to customize the features of a
7 ;;;; local build of SBCL is not to edit this file, but instead to
8 ;;;; tweak customize-target-features.lisp. E.g. you can use code like
11 ;;;; (flet ((enable (x) (pushnew x list))
12 ;;;; (disable (x) (setf list (remove x list))))
13 ;;;; #+nil (enable :sb-show)
14 ;;;; (enable :sb-after-xc-core)
15 ;;;; #+nil (disable :sb-doc)
17 ;;;; That way, because customize-target-features.lisp is in
18 ;;;; .cvsignore, your local changes will remain local even if you use
19 ;;;; "cvs diff" to submit patches to SBCL.
21 ;;;; This software is part of the SBCL system. See the README file for
22 ;;;; more information.
24 ;;;; This software is derived from the CMU CL system, which was
25 ;;;; written at Carnegie Mellon University and released into the
26 ;;;; public domain. The software is in the public domain and is
27 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
28 ;;;; files for more information.
32 ;; features present in all builds
37 ;; FIXME: Isn't there a :x3jsomething feature which we should set too?
42 ;; Douglas Thomas Crosher's conservative generational GC (the only one
43 ;; we currently support for X86)
46 ;; We're running under a UNIX. This is sort of redundant, and it was also
47 ;; sort of redundant under CMU CL, which we inherited it from: neither SBCL
48 ;; nor CMU CL supports anything but UNIX (and "technically not UNIX"es
49 ;; such as *BSD and Linux). But someday, maybe we might, and in that case
50 ;; we'd presumably remove this, so its presence conveys the information
51 ;; that the system isn't one which follows such a change.
55 ;; features present in this particular build
58 ;; Setting this enables the compilation of documentation strings
59 ;; from the system sources into the target Lisp executable.
60 ;; Traditional Common Lisp folk will want this option set.
61 ;; I (WHN) made it optional because I came to Common Lisp from
62 ;; C++ through Scheme, so I'm accustomed to asking
63 ;; Emacs about things that I'm curious about instead of asking
64 ;; the executable I'm running.
67 ;; Do regression and other tests when building the system. You
68 ;; might or might not want this if you're not a developer,
69 ;; depending on how paranoid you are. You probably do want it if
70 ;; you are a developer.
73 ;; Make more debugging information available (for debugging SBCL
74 ;; itself). If you aren't hacking or troubleshooting SBCL itself,
75 ;; you probably don't want this set.
77 ;; At least two varieties of debugging information are enabled by this
79 ;; * SBCL is compiled with a higher level of OPTIMIZE DEBUG, so that
80 ;; the debugger can tell more about the state of the system.
81 ;; * Various code to print debugging messages, and similar debugging code,
82 ;; is compiled only when this feature is present.
84 ;; Note that the extra information recorded by the compiler at
85 ;; this higher level of OPTIMIZE DEBUG includes the source location
86 ;; forms. In order for the debugger to use this information, it has to
87 ;; re-READ the source file. In an ordinary installation of SBCL, this
88 ;; re-READing may not work very well, for either of two reasons:
89 ;; * The sources aren't present on the system in the same location that
90 ;; they were on the system where SBCL was compiled.
91 ;; * SBCL is using the standard readtable, without the added hackage
92 ;; which allows it to handle things like target features.
93 ;; If you want to be able to use the extra debugging information,
94 ;; therefore, be sure to keep the sources around, and run with the
95 ;; readtable configured so that the system sources can be read.
98 ;; Build SBCL with the old CMU CL low level debugger, "ldb". If
99 ;; are aren't messing with CMU CL at a very low level (e.g.
100 ;; trying to diagnose GC problems) you shouldn't need this.
103 ;; This isn't really a target Lisp feature at all, but controls
104 ;; whether the build process produces an after-xc.core file. This
105 ;; can be useful for shortening the edit/compile/debug cycle if
106 ;; you're messing around with low-level internals of the system,
107 ;; as in slam.sh. Otherwise you don't need it.
110 ;; Enable extra debugging output in the assem.lisp assembler/scheduler
111 ;; code. (This is the feature which was called :DEBUG in the
112 ;; original CMU CL code.)
115 ;; Setting this makes SBCL more "fluid", i.e. more amenable to
116 ;; modification at runtime, by suppressing various INLINE declarations,
117 ;; compiler macro definitions, FREEZE-TYPE declarations; and by
118 ;; suppressing various burning-our-ships-behind-us actions after
119 ;; initialization is complete; and so forth. This tends to clobber the
120 ;; performance of the system, so unless you have some special need for
121 ;; this when hacking SBCL itself, you don't want this set.
124 ;; Enable code for collecting statistics on usage of various operations,
125 ;; useful for performance tuning of the SBCL system itself. This code
126 ;; is probably pretty stale (having not been tested since the fork from
127 ;; base CMU CL) but might nonetheless be a useful starting point for
128 ;; anyone who wants to collect such statistics in the future.
131 ;; Peter Van Eynde's increase-bulletproofness code
133 ;; This is not maintained or tested in current SBCL, but I haven't
134 ;; gone out of my way to remove or break it, either.
137 ; :high-security-support
139 ;; multiprocessing support
141 ;; This is not maintained or tested in current SBCL. I haven't gone out
142 ;; of my way to break it, but since it's derived from an old version of
143 ;; CMU CL where multiprocessing was pretty shaky, it's likely to be very
145 ;; :MP enables multiprocessing
146 ;; :MP-I486 is used, only within the multiprocessing code, to control
147 ;; what seems to control processor-version-specific code. It's
148 ;; probably for 486 or later, i.e. could be set as long as
149 ;; you know you're not running on a 386, but it doesn't seem
150 ;; to be documented anywhere, so that's just a guess.
154 ;; This affects the definition of a lot of things in bignum.lisp. It
155 ;; doesn't seem to be documented anywhere what systems it might apply
156 ;; to. It doesn't seem to be needed for X86 systems anyway.
159 ;; This is probably true for some processor types, but not X86. It
160 ;; affects a lot of floating point code.
161 ; :negative-zero-is-not-zero
163 ;; This is set in classic CMU CL, and presumably there it means
164 ;; that the floating point arithmetic implementation
165 ;; conforms to IEEE's standard. Here it definitely means that the
166 ;; floating point arithmetic implementation conforms to IEEE's standard.
167 ;; I (WHN 19990702) haven't tried to verify
168 ;; that it does conform, but it should at least mostly conform (because
169 ;; the underlying x86 hardware tries).
172 ;; This seems to be the pre-GENCGC garbage collector for CMU CL, which was
173 ;; AFAIK never supported for the X86.
176 ;; CMU CL had, and we inherited, code to support 80-bit LONG-FLOAT on the x86
177 ;; architecture. Nothing has been done to actively destroy the long float
178 ;; support, but it hasn't been thoroughly maintained, and needs at least
179 ;; some maintenance before it will work. (E.g. the LONG-FLOAT-only parts of
180 ;; genesis are still implemented in terms of unportable CMU CL functions
181 ;; which are not longer available at genesis time in SBCL.) A deeper
182 ;; problem is SBCL's bootstrap process implicitly assumes that the
183 ;; cross-compilation host will be able to make the same distinctions
184 ;; between floating point types that it does. This assumption is
185 ;; fundamentally sleazy, even though in practice it's unlikely to break down
186 ;; w.r.t. distinguishing SINGLE-FLOAT from DOUBLE-FLOAT; it's much more
187 ;; likely to break down w.r.t. distinguishing DOUBLE-FLOAT from LONG-FLOAT.
188 ;; Still it's likely to be quite doable to get LONG-FLOAT support working
189 ;; again, if anyone's sufficiently motivated.
193 ;; miscellaneous notes on other things which could have special significance
194 ;; in the *FEATURES* list
197 ;; notes on the :NIL and :IGNORE features:
199 ;; #+NIL is used to comment out forms. Occasionally #+IGNORE is used
200 ;; for this too. So don't use :NIL or :IGNORE as the names of features..
202 ;; notes on :SB-XC and :SB-XC-HOST features (which aren't controlled by this
203 ;; file, but are instead temporarily pushed onto *FEATURES* or
204 ;; *TARGET-FEATURES* during some phases of cross-compilation):
206 ;; :SB-XC-HOST stands for "cross-compilation host" and is in *FEATURES*
207 ;; during the first phase of cross-compilation bootstrapping, when the
208 ;; host Lisp is being used to compile the cross-compiler.
210 ;; :SB-XC stands for "cross compiler", and is in *FEATURES* during the second
211 ;; phase of cross-compilation bootstrapping, when the cross-compiler is
212 ;; being used to create the first target Lisp.
214 ;; notes on the :SB-ASSEMBLING feature (which isn't controlled by
217 ;; This is a flag for whether we're in the assembler. It's
218 ;; temporarily pushed onto the *FEATURES* list in the setup for
219 ;; the ASSEMBLE-FILE function. It would be a bad idea
220 ;; to use it as a name for a permanent feature.
222 ;; notes on local features (which are set automatically by the
223 ;; configuration script, and should not be set here unless you
224 ;; really, really know what you're doing):
226 ;; machine architecture features:
228 ;; any Intel 386 or better, or compatibles like the AMD K6 or K7
230 ;; DEC/Compaq Alpha CPU
231 ;; (No other CPUs are supported by SBCL as of 0.6.12.15, but SPARC or
232 ;; PowerPC support could be ported from CMU CL if anyone is
233 ;; sufficiently motivated to do so, or if you're *really* motivated,
234 ;; you could write a port from scratch for a new CPU architecture.)
235 ;; (CMU CL also had a :pentium feature, which affected the definition
236 ;; of some floating point vops. It was present but not enabled or
237 ;; documented in the CMU CL code that SBCL is derived from, and is
238 ;; present but stale in SBCL as of 0.6.12.)
240 ;; operating system features:
241 ;; :linux = We're intended to run under some version of Linux.
242 ;; :bsd = We're intended to run under some version of BSD Unix. (This
243 ;; is not exclusive with the features which indicate which
244 ;; particular version of BSD we're intended to run under.)
245 ;; :freebsd = We're intended to run under FreeBSD.
246 ;; :openbsd = We're intended to run under FreeBSD.
247 ;; (No others are supported by SBCL as of 0.6.7, but :hpux or
248 ;; :solaris support could be ported from CMU CL if anyone is
249 ;; sufficiently motivated to do so, and it'd even be possible,
250 ;; though harder, to port the system to Microsoft Windows.)