xref: /openbsd-src/gnu/usr.bin/gcc/gcc/doc/install-old.texi (revision f6aab3d83b51b91c24247ad2c2573574de475a82)
1@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
2@c This is part of the GCC manual.
3@c For copying conditions, see the file install.texi.
4
5@ifnothtml
6@comment node-name,     next,          previous, up
7@node    Old, GNU Free Documentation License, Specific, Top
8@end ifnothtml
9@html
10<h1 align="center">Old installation documentation</h1>
11@end html
12@ifnothtml
13@chapter Old installation documentation
14@end ifnothtml
15
16Note most of this information is out of date and superseded by the
17previous chapters of this manual.  It is provided for historical
18reference only, because of a lack of volunteers to merge it into the
19main manual.
20
21@ifnothtml
22@menu
23* Configurations::    Configurations Supported by GNU CC.
24* Cross-Compiler::   Building and installing a cross-compiler.
25* VMS Install::   See below for installation on VMS.
26@end menu
27@end ifnothtml
28
29Here is the procedure for installing GNU CC on a GNU or Unix system.
30See @ref{VMS Install}, for VMS systems.
31
32@enumerate
33@item
34If you have chosen a configuration for GNU CC which requires other GNU
35tools (such as GAS or the GNU linker) instead of the standard system
36tools, install the required tools in the build directory under the names
37@file{as}, @file{ld} or whatever is appropriate.
38
39Alternatively, you can do subsequent compilation using a value of the
40@code{PATH} environment variable such that the necessary GNU tools come
41before the standard system tools.
42
43@item
44Specify the host, build and target machine configurations.  You do this
45when you run the @file{configure} script.
46
47The @dfn{build} machine is the system which you are using, the
48@dfn{host} machine is the system where you want to run the resulting
49compiler (normally the build machine), and the @dfn{target} machine is
50the system for which you want the compiler to generate code.
51
52If you are building a compiler to produce code for the machine it runs
53on (a native compiler), you normally do not need to specify any operands
54to @file{configure}; it will try to guess the type of machine you are on
55and use that as the build, host and target machines.  So you don't need
56to specify a configuration when building a native compiler unless
57@file{configure} cannot figure out what your configuration is or guesses
58wrong.
59
60In those cases, specify the build machine's @dfn{configuration name}
61with the @option{--host} option; the host and target will default to be
62the same as the host machine.  (If you are building a cross-compiler,
63see @ref{Cross-Compiler}.)
64
65Here is an example:
66
67@smallexample
68./configure --host=sparc-sun-sunos4.1
69@end smallexample
70
71A configuration name may be canonical or it may be more or less
72abbreviated.
73
74A canonical configuration name has three parts, separated by dashes.
75It looks like this: @samp{@var{cpu}-@var{company}-@var{system}}.
76(The three parts may themselves contain dashes; @file{configure}
77can figure out which dashes serve which purpose.)  For example,
78@samp{m68k-sun-sunos4.1} specifies a Sun 3.
79
80You can also replace parts of the configuration by nicknames or aliases.
81For example, @samp{sun3} stands for @samp{m68k-sun}, so
82@samp{sun3-sunos4.1} is another way to specify a Sun 3.
83
84You can specify a version number after any of the system types, and some
85of the CPU types.  In most cases, the version is irrelevant, and will be
86ignored.  So you might as well specify the version if you know it.
87
88See @ref{Configurations}, for a list of supported configuration names and
89notes on many of the configurations.  You should check the notes in that
90section before proceeding any further with the installation of GNU CC@.
91
92@end enumerate
93
94@ifnothtml
95@node Configurations, Cross-Compiler, , Old
96@section Configurations Supported by GNU CC
97@end ifnothtml
98@html
99<h2>@anchor{Configurations}Configurations Supported by GNU CC</h2>
100@end html
101@cindex configurations supported by GNU CC
102
103Here are the possible CPU types:
104
105@quotation
106@c gmicro, fx80, spur and tahoe omitted since they don't work.
1071750a, a29k, alpha, arm, avr, c@var{n}, clipper, dsp16xx, elxsi, fr30, h8300,
108hppa1.0, hppa1.1, i370, i386, i486, i586, i686, i786, i860, i960, ip2k, m32r,
109m68000, m68k, m6811, m6812, m88k, mcore, mips, mipsel, mips64, mips64el,
110mn10200, mn10300, ns32k, pdp11, powerpc, powerpcle, romp, rs6000, sh, sparc,
111sparclite, sparc64, v850, vax, we32k.
112@end quotation
113
114Here are the recognized company names.  As you can see, customary
115abbreviations are used rather than the longer official names.
116
117@c What should be done about merlin, tek*, dolphin?
118@quotation
119acorn, alliant, altos, apollo, apple, att, bull,
120cbm, convergent, convex, crds, dec, dg, dolphin,
121elxsi, encore, harris, hitachi, hp, ibm, intergraph, isi,
122mips, motorola, ncr, next, ns, omron, plexus,
123sequent, sgi, sony, sun, tti, unicom, wrs.
124@end quotation
125
126The company name is meaningful only to disambiguate when the rest of
127the information supplied is insufficient.  You can omit it, writing
128just @samp{@var{cpu}-@var{system}}, if it is not needed.  For example,
129@samp{vax-ultrix4.2} is equivalent to @samp{vax-dec-ultrix4.2}.
130
131Here is a list of system types:
132
133@quotation
134386bsd, aix, acis, amigaos, aos, aout, aux, bosx, bsd, clix, coff, ctix, cxux,
135dgux, dynix, ebmon, ecoff, elf, esix, freebsd, hms, genix, gnu, linux,
136linux-gnu, hiux, hpux, iris, irix, isc, luna, lynxos, mach, minix, msdos, mvs,
137netbsd, newsos, nindy, ns, osf, osfrose, ptx, riscix, riscos, rtu, sco, sim,
138solaris, sunos, sym, sysv, udi, ultrix, unicos, uniplus, unos, vms, vsta,
139vxworks, winnt, xenix.
140@end quotation
141
142@noindent
143You can omit the system type; then @file{configure} guesses the
144operating system from the CPU and company.
145
146You can add a version number to the system type; this may or may not
147make a difference.  For example, you can write @samp{bsd4.3} or
148@samp{bsd4.4} to distinguish versions of BSD@.  In practice, the version
149number is most needed for @samp{sysv3} and @samp{sysv4}, which are often
150treated differently.
151
152@samp{linux-gnu} is the canonical name for the GNU/Linux target; however
153GNU CC will also accept @samp{linux}.  The version of the kernel in use is
154not relevant on these systems.  A suffix such as @samp{libc1} or @samp{aout}
155distinguishes major versions of the C library; all of the suffixed versions
156are obsolete.
157
158If you specify an impossible combination such as @samp{i860-dg-vms},
159then you may get an error message from @file{configure}, or it may
160ignore part of the information and do the best it can with the rest.
161@file{configure} always prints the canonical name for the alternative
162that it used.  GNU CC does not support all possible alternatives.
163
164Often a particular model of machine has a name.  Many machine names are
165recognized as aliases for CPU/company combinations.  Thus, the machine
166name @samp{sun3}, mentioned above, is an alias for @samp{m68k-sun}.
167Sometimes we accept a company name as a machine name, when the name is
168popularly used for a particular machine.  Here is a table of the known
169machine names:
170
171@quotation
1723300, 3b1, 3b@var{n}, 7300, altos3068, altos,
173apollo68, att-7300, balance,
174convex-c@var{n}, crds, decstation-3100,
175decstation, delta, encore,
176fx2800, gmicro, hp7@var{nn}, hp8@var{nn},
177hp9k2@var{nn}, hp9k3@var{nn}, hp9k7@var{nn},
178hp9k8@var{nn}, iris4d, iris, isi68,
179m3230, magnum, merlin, miniframe,
180mmax, news-3600, news800, news, next,
181pbd, pc532, pmax, powerpc, powerpcle, ps2, risc-news,
182rtpc, sun2, sun386i, sun386, sun3,
183sun4, symmetry, tower-32, tower.
184@end quotation
185
186@noindent
187Remember that a machine name specifies both the cpu type and the company
188name.
189If you want to install your own homemade configuration files, you can
190use @samp{local} as the company name to access them.  If you use
191configuration @samp{@var{cpu}-local}, the configuration name
192without the cpu prefix
193is used to form the configuration file names.
194
195Thus, if you specify @samp{m68k-local}, configuration uses
196files @file{m68k.md}, @file{local.h}, @file{m68k.c},
197@file{xm-local.h}, @file{t-local}, and @file{x-local}, all in the
198directory @file{config/m68k}.
199
200Here is a list of configurations that have special treatment or special
201things you must know:
202
203@table @samp
204@item vax-dec-vms
205See @ref{VMS Install}, for details on how to install GNU CC on VMS@.
206@end table
207
208@ifnothtml
209@node Cross-Compiler, VMS Install, Configurations, Old
210@section Building and Installing a Cross-Compiler
211@end ifnothtml
212@html
213<h2>@anchor{Cross-Compiler}Building and Installing a Cross-Compiler</h2>
214@end html
215@cindex cross-compiler, installation
216
217GNU CC can function as a cross-compiler for many machines, but not all.
218
219@itemize @bullet
220@item
221Cross-compilers for the Mips as target using the Mips assembler
222currently do not work, because the auxiliary programs
223@file{mips-tdump.c} and @file{mips-tfile.c} can't be compiled on
224anything but a Mips.  It does work to cross compile for a Mips
225if you use the GNU assembler and linker.
226
227@item
228Cross-compilers between machines with different floating point formats
229have not all been made to work.  GNU CC now has a floating point
230emulator with which these can work, but each target machine description
231needs to be updated to take advantage of it.
232
233@item
234Cross-compilation between machines of different word sizes is
235somewhat problematic and sometimes does not work.
236@end itemize
237
238Since GNU CC generates assembler code, you probably need a
239cross-assembler that GNU CC can run, in order to produce object files.
240If you want to link on other than the target machine, you need a
241cross-linker as well.  You also need header files and libraries suitable
242for the target machine that you can install on the host machine.
243
244@ifnothtml
245@menu
246* Steps of Cross::      Using a cross-compiler involves several steps
247                          that may be carried out on different machines.
248* Configure Cross::     Configuring a cross-compiler.
249* Tools and Libraries:: Where to put the linker and assembler, and the C library.
250* Cross Headers::       Finding and installing header files
251                          for a cross-compiler.
252* Build Cross::         Actually compiling the cross-compiler.
253@end menu
254@end ifnothtml
255
256@ifnothtml
257@node Steps of Cross, Configure Cross, , Cross-Compiler
258@subsection Steps of Cross-Compilation
259@end ifnothtml
260@html
261<h2>Steps of Cross-Compilation</h2>
262@end html
263
264To compile and run a program using a cross-compiler involves several
265steps:
266
267@itemize @bullet
268@item
269Run the cross-compiler on the host machine to produce assembler files
270for the target machine.  This requires header files for the target
271machine.
272
273@item
274Assemble the files produced by the cross-compiler.  You can do this
275either with an assembler on the target machine, or with a
276cross-assembler on the host machine.
277
278@item
279Link those files to make an executable.  You can do this either with a
280linker on the target machine, or with a cross-linker on the host
281machine.  Whichever machine you use, you need libraries and certain
282startup files (typically @file{crt@dots{}.o}) for the target machine.
283@end itemize
284
285It is most convenient to do all of these steps on the same host machine,
286since then you can do it all with a single invocation of GNU CC@.  This
287requires a suitable cross-assembler and cross-linker.  For some targets,
288the GNU assembler and linker are available.
289
290@ifnothtml
291@node Configure Cross, Tools and Libraries, Steps of Cross, Cross-Compiler
292@subsection Configuring a Cross-Compiler
293@end ifnothtml
294@html
295<h2>Configuring a Cross-Compiler</h2>
296@end html
297
298To build GNU CC as a cross-compiler, you start out by running
299@file{configure}.  Use the @option{--target=@var{target}} to specify the
300target type.  If @file{configure} was unable to correctly identify the
301system you are running on, also specify the @option{--build=@var{build}}
302option.  For example, here is how to configure for a cross-compiler that
303produces code for an HP 68030 system running BSD on a system that
304@file{configure} can correctly identify:
305
306@smallexample
307./configure --target=m68k-hp-bsd4.3
308@end smallexample
309
310@ifnothtml
311@node Tools and Libraries, Cross Headers, Configure Cross, Cross-Compiler
312@subsection Tools and Libraries for a Cross-Compiler
313@end ifnothtml
314@html
315<h2>Tools and Libraries for a Cross-Compiler</h2>
316@end html
317
318If you have a cross-assembler and cross-linker available, you should
319install them now.  Put them in the directory
320@file{/usr/local/@var{target}/bin}.  Here is a table of the tools
321you should put in this directory:
322
323@table @file
324@item as
325This should be the cross-assembler.
326
327@item ld
328This should be the cross-linker.
329
330@item ar
331This should be the cross-archiver: a program which can manipulate
332archive files (linker libraries) in the target machine's format.
333
334@item ranlib
335This should be a program to construct a symbol table in an archive file.
336@end table
337
338The installation of GNU CC will find these programs in that directory,
339and copy or link them to the proper place to for the cross-compiler to
340find them when run later.
341
342The easiest way to provide these files is to build the Binutils package
343and GAS@.  Configure them with the same @option{--host} and @option{--target}
344options that you use for configuring GNU CC, then build and install
345them.  They install their executables automatically into the proper
346directory.  Alas, they do not support all the targets that GNU CC
347supports.
348
349If you want to install libraries to use with the cross-compiler, such as
350a standard C library, put them in the directory
351@file{/usr/local/@var{target}/lib}; installation of GNU CC copies
352all the files in that subdirectory into the proper place for GNU CC to
353find them and link with them.  Here's an example of copying some
354libraries from a target machine:
355
356@example
357ftp @var{target-machine}
358lcd /usr/local/@var{target}/lib
359cd /lib
360get libc.a
361cd /usr/lib
362get libg.a
363get libm.a
364quit
365@end example
366
367@noindent
368The precise set of libraries you'll need, and their locations on
369the target machine, vary depending on its operating system.
370
371@cindex start files
372Many targets require ``start files'' such as @file{crt0.o} and
373@file{crtn.o} which are linked into each executable; these too should be
374placed in @file{/usr/local/@var{target}/lib}.  There may be several
375alternatives for @file{crt0.o}, for use with profiling or other
376compilation options.  Check your target's definition of
377@code{STARTFILE_SPEC} to find out what start files it uses.
378Here's an example of copying these files from a target machine:
379
380@example
381ftp @var{target-machine}
382lcd /usr/local/@var{target}/lib
383prompt
384cd /lib
385mget *crt*.o
386cd /usr/lib
387mget *crt*.o
388quit
389@end example
390
391@ifnothtml
392@node Cross Headers, Build Cross, Tools and Libraries, Cross-Compiler
393@subsection Cross-Compilers and Header Files
394@end ifnothtml
395@html
396<h2>Cross-Compilers and Header Files</h2>
397@end html
398
399If you are cross-compiling a standalone program or a program for an
400embedded system, then you may not need any header files except the few
401that are part of GNU CC (and those of your program).  However, if you
402intend to link your program with a standard C library such as
403@file{libc.a}, then you probably need to compile with the header files
404that go with the library you use.
405
406The GNU C compiler does not come with these files, because (1) they are
407system-specific, and (2) they belong in a C library, not in a compiler.
408
409If the GNU C library supports your target machine, then you can get the
410header files from there (assuming you actually use the GNU library when
411you link your program).
412
413If your target machine comes with a C compiler, it probably comes with
414suitable header files also.  If you make these files accessible from the host
415machine, the cross-compiler can use them also.
416
417Otherwise, you're on your own in finding header files to use when
418cross-compiling.
419
420When you have found suitable header files, you should put them in the
421directory @file{/usr/local/@var{target}/include}, before building the
422cross compiler.  Then installation will run fixincludes properly and
423install the corrected versions of the header files where the compiler
424will use them.
425
426Provide the header files before you build the cross-compiler, because
427the build stage actually runs the cross-compiler to produce parts of
428@file{libgcc.a}.  (These are the parts that @emph{can} be compiled with
429GNU CC@.)  Some of them need suitable header files.
430
431Here's an example showing how to copy the header files from a target
432machine.  On the target machine, do this:
433
434@example
435(cd /usr/include; tar cf - .) > tarfile
436@end example
437
438Then, on the host machine, do this:
439
440@example
441ftp @var{target-machine}
442lcd /usr/local/@var{target}/include
443get tarfile
444quit
445tar xf tarfile
446@end example
447
448@ifnothtml
449@node Build Cross, , Cross Headers, Cross-Compiler
450@subsection Actually Building the Cross-Compiler
451@end ifnothtml
452@html
453<h2>Actually Building the Cross-Compiler</h2>
454@end html
455
456Now you can proceed just as for compiling a single-machine compiler
457through the step of building stage 1.
458
459Do not try to build stage 2 for a cross-compiler.  It doesn't work to
460rebuild GNU CC as a cross-compiler using the cross-compiler, because
461that would produce a program that runs on the target machine, not on the
462host.  For example, if you compile a 386-to-68030 cross-compiler with
463itself, the result will not be right either for the 386 (because it was
464compiled into 68030 code) or for the 68030 (because it was configured
465for a 386 as the host).  If you want to compile GNU CC into 68030 code,
466whether you compile it on a 68030 or with a cross-compiler on a 386, you
467must specify a 68030 as the host when you configure it.
468
469To install the cross-compiler, use @samp{make install}, as usual.
470
471@ifnothtml
472@node VMS Install, , Cross-Compiler, Old
473@section Installing GNU CC on VMS
474@end ifnothtml
475@html
476<h2>@anchor{VMS Install}Installing GNU CC on VMS</h2>
477@end html
478@cindex VMS installation
479@cindex installing GNU CC on VMS
480
481The VMS version of GNU CC is distributed in a backup saveset containing
482both source code and precompiled binaries.
483
484To install the @file{gcc} command so you can use the compiler easily, in
485the same manner as you use the VMS C compiler, you must install the VMS CLD
486file for GNU CC as follows:
487
488@enumerate
489@item
490Define the VMS logical names @samp{GNU_CC} and @samp{GNU_CC_INCLUDE}
491to point to the directories where the GNU CC executables
492(@file{gcc-cpp.exe}, @file{gcc-cc1.exe}, etc.) and the C include files are
493kept respectively.  This should be done with the commands:
494
495@smallexample
496$ assign /system /translation=concealed -
497  disk:[gcc.] gnu_cc
498$ assign /system /translation=concealed -
499  disk:[gcc.include.] gnu_cc_include
500@end smallexample
501
502@noindent
503with the appropriate disk and directory names.  These commands can be
504placed in your system startup file so they will be executed whenever
505the machine is rebooted.  You may, if you choose, do this via the
506@file{GCC_INSTALL.COM} script in the @file{[GCC]} directory.
507
508@item
509Install the @file{GCC} command with the command line:
510
511@smallexample
512$ set command /table=sys$common:[syslib]dcltables -
513  /output=sys$common:[syslib]dcltables gnu_cc:[000000]gcc
514$ install replace sys$common:[syslib]dcltables
515@end smallexample
516
517@item
518To install the help file, do the following:
519
520@smallexample
521$ library/help sys$library:helplib.hlb gcc.hlp
522@end smallexample
523
524@noindent
525Now you can invoke the compiler with a command like @samp{gcc /verbose
526file.c}, which is equivalent to the command @samp{gcc -v -c file.c} in
527Unix.
528@end enumerate
529
530If you wish to use GNU C++ you must first install GNU CC, and then
531perform the following steps:
532
533@enumerate
534@item
535Define the VMS logical name @samp{GNU_GXX_INCLUDE} to point to the
536directory where the preprocessor will search for the C++ header files.
537This can be done with the command:
538
539@smallexample
540$ assign /system /translation=concealed -
541  disk:[gcc.gxx_include.] gnu_gxx_include
542@end smallexample
543
544@noindent
545with the appropriate disk and directory name.  If you are going to be
546using a C++ runtime library, this is where its install procedure will install
547its header files.
548
549@item
550Obtain the file @file{gcc-cc1plus.exe}, and place this in the same
551directory that @file{gcc-cc1.exe} is kept.
552
553The GNU C++ compiler can be invoked with a command like @samp{gcc /plus
554/verbose file.cc}, which is equivalent to the command @samp{g++ -v -c
555file.cc} in Unix.
556@end enumerate
557
558We try to put corresponding binaries and sources on the VMS distribution
559tape.  But sometimes the binaries will be from an older version than the
560sources, because we don't always have time to update them.  (Use the
561@samp{/version} option to determine the version number of the binaries and
562compare it with the source file @file{version.c} to tell whether this is
563so.)  In this case, you should use the binaries you get to recompile the
564sources.  If you must recompile, here is how:
565
566@enumerate
567@item
568Execute the command procedure @file{vmsconfig.com} to set up the files
569@file{tm.h}, @file{config.h}, @file{aux-output.c}, and @file{md.}, and
570to create files @file{tconfig.h} and @file{hconfig.h}.  This procedure
571also creates several linker option files used by @file{make-cc1.com} and
572a data file used by @file{make-l2.com}.
573
574@smallexample
575$ @@vmsconfig.com
576@end smallexample
577
578@item
579Setup the logical names and command tables as defined above.  In
580addition, define the VMS logical name @samp{GNU_BISON} to point at the
581to the directories where the Bison executable is kept.  This should be
582done with the command:
583
584@smallexample
585$ assign /system /translation=concealed -
586  disk:[bison.] gnu_bison
587@end smallexample
588
589You may, if you choose, use the @file{INSTALL_BISON.COM} script in the
590@file{[BISON]} directory.
591
592@item
593Install the @samp{BISON} command with the command line:
594
595@smallexample
596$ set command /table=sys$common:[syslib]dcltables -
597  /output=sys$common:[syslib]dcltables -
598  gnu_bison:[000000]bison
599$ install replace sys$common:[syslib]dcltables
600@end smallexample
601
602@item
603Type @samp{@@make-gcc} to recompile everything, or submit the file
604@file{make-gcc.com} to a batch queue.  If you wish to build the GNU C++
605compiler as well as the GNU CC compiler, you must first edit
606@file{make-gcc.com} and follow the instructions that appear in the
607comments.
608
609@item
610In order to use GCC, you need a library of functions which GCC compiled code
611will call to perform certain tasks, and these functions are defined in the
612file @file{libgcc2.c}.  To compile this you should use the command procedure
613@file{make-l2.com}, which will generate the library @file{libgcc2.olb}.
614@file{libgcc2.olb} should be built using the compiler built from
615the same distribution that @file{libgcc2.c} came from, and
616@file{make-gcc.com} will automatically do all of this for you.
617
618To install the library, use the following commands:
619
620@smallexample
621$ library gnu_cc:[000000]gcclib/delete=(new,eprintf)
622$ library gnu_cc:[000000]gcclib/delete=L_*
623$ library libgcc2/extract=*/output=libgcc2.obj
624$ library gnu_cc:[000000]gcclib libgcc2.obj
625@end smallexample
626
627The first command simply removes old modules that will be replaced with
628modules from @file{libgcc2} under different module names.  The modules
629@code{new} and @code{eprintf} may not actually be present in your
630@file{gcclib.olb}---if the VMS librarian complains about those modules
631not being present, simply ignore the message and continue on with the
632next command.  The second command removes the modules that came from the
633previous version of the library @file{libgcc2.c}.
634
635Whenever you update the compiler on your system, you should also update the
636library with the above procedure.
637
638@item
639You may wish to build GCC in such a way that no files are written to the
640directory where the source files reside.  An example would be the when
641the source files are on a read-only disk.  In these cases, execute the
642following DCL commands (substituting your actual path names):
643
644@smallexample
645$ assign dua0:[gcc.build_dir.]/translation=concealed, -
646         dua1:[gcc.source_dir.]/translation=concealed  gcc_build
647$ set default gcc_build:[000000]
648@end smallexample
649
650@noindent
651where the directory @file{dua1:[gcc.source_dir]} contains the source
652code, and the directory @file{dua0:[gcc.build_dir]} is meant to contain
653all of the generated object files and executables.  Once you have done
654this, you can proceed building GCC as described above.  (Keep in mind
655that @file{gcc_build} is a rooted logical name, and thus the device
656names in each element of the search list must be an actual physical
657device name rather than another rooted logical name).
658
659@item
660@strong{If you are building GNU CC with a previous version of GNU CC,
661you also should check to see that you have the newest version of the
662assembler}.  In particular, GNU CC version 2 treats global constant
663variables slightly differently from GNU CC version 1, and GAS version
6641.38.1 does not have the patches required to work with GCC version 2.
665If you use GAS 1.38.1, then @code{extern const} variables will not have
666the read-only bit set, and the linker will generate warning messages
667about mismatched psect attributes for these variables.  These warning
668messages are merely a nuisance, and can safely be ignored.
669
670@item
671If you want to build GNU CC with the VAX C compiler, you will need to
672make minor changes in @file{make-cccp.com} and @file{make-cc1.com}
673to choose alternate definitions of @code{CC}, @code{CFLAGS}, and
674@code{LIBS}.  See comments in those files.  However, you must
675also have a working version of the GNU assembler (GNU as, aka GAS) as
676it is used as the back end for GNU CC to produce binary object modules
677and is not included in the GNU CC sources.  GAS is also needed to
678compile @file{libgcc2} in order to build @file{gcclib} (see above);
679@file{make-l2.com} expects to be able to find it operational in
680@file{gnu_cc:[000000]gnu-as.exe}.
681
682To use GNU CC on VMS, you need the VMS driver programs
683@file{gcc.exe}, @file{gcc.com}, and @file{gcc.cld}.  They are
684distributed with the VMS binaries (@file{gcc-vms}) rather than the
685GNU CC sources.  GAS is also included in @file{gcc-vms}, as is Bison.
686
687Once you have successfully built GNU CC with VAX C, you should use the
688resulting compiler to rebuild itself.  Before doing this, be sure to
689restore the @code{CC}, @code{CFLAGS}, and @code{LIBS} definitions in
690@file{make-cccp.com} and @file{make-cc1.com}.  The second generation
691compiler will be able to take advantage of many optimizations that must
692be suppressed when building with other compilers.
693@end enumerate
694
695Under previous versions of GNU CC, the generated code would occasionally
696give strange results when linked with the sharable @file{VAXCRTL} library.
697Now this should work.
698
699Even with this version, however, GNU CC itself should not be linked with
700the sharable @file{VAXCRTL}.  The version of @code{qsort} in
701@file{VAXCRTL} has a bug (known to be present in VMS versions V4.6
702through V5.5) which causes the compiler to fail.
703
704The executables are generated by @file{make-cc1.com} and
705@file{make-cccp.com} use the object library version of @file{VAXCRTL} in
706order to make use of the @code{qsort} routine in @file{gcclib.olb}.  If
707you wish to link the compiler executables with the shareable image
708version of @file{VAXCRTL}, you should edit the file @file{tm.h} (created
709by @file{vmsconfig.com}) to define the macro @code{QSORT_WORKAROUND}.
710
711@code{QSORT_WORKAROUND} is always defined when GNU CC is compiled with
712VAX C, to avoid a problem in case @file{gcclib.olb} is not yet
713available.
714