(gcc.info)Configurations


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Configurations Supported by GNU CC
==================================

   Here are the possible CPU types:

     1750a, a29k, alpha, arm, cN, clipper, dsp16xx, elxsi, h8300,
     hppa1.0, hppa1.1, i370, i386, i486, i586, i860, i960, m68000, m68k,
     m88k, mips, mipsel, mips64, mips64el, ns32k, powerpc, powerpcle,
     pyramid, romp, rs6000, sh, sparc, sparclite, sparc64, vax, we32k.

   Here are the recognized company names.  As you can see, customary
abbreviations are used rather than the longer official names.

     acorn, alliant, altos, apollo, att, bull, cbm, convergent, convex,
     crds, dec, dg, dolphin, elxsi, encore, harris, hitachi, hp, ibm,
     intergraph, isi, mips, motorola, ncr, next, ns, omron, plexus,
     sequent, sgi, sony, sun, tti, unicom, wrs.

   The company name is meaningful only to disambiguate when the rest of
the information supplied is insufficient.  You can omit it, writing
just `CPU-SYSTEM', if it is not needed.  For example, `vax-ultrix4.2'
is equivalent to `vax-dec-ultrix4.2'.

   Here is a list of system types:

     386bsd, aix, acis, amigados, aos, aout, bosx, bsd, clix, coff,
     ctix, cxux, dgux, dynix, ebmon, ecoff, elf, esix, freebsd, hms,
     genix, gnu, gnu/linux, hiux, hpux, iris, irix, isc, luna, lynxos,
     mach, minix, msdos, mvs, netbsd, newsos, nindy, ns, osf, osfrose,
     ptx, riscix, riscos, rtu, sco, sim, solaris, sunos, sym, sysv,
     udi, ultrix, unicos, uniplus, unos, vms, vsta, vxworks, winnt,
     xenix.

You can omit the system type; then `configure' guesses the operating
system from the CPU and company.

   You can add a version number to the system type; this may or may not
make a difference.  For example, you can write `bsd4.3' or `bsd4.4' to
distinguish versions of BSD.  In practice, the version number is most
needed for `sysv3' and `sysv4', which are often treated differently.

   If you specify an impossible combination such as `i860-dg-vms', then
you may get an error message from `configure', or it may ignore part of
the information and do the best it can with the rest.  `configure'
always prints the canonical name for the alternative that it used.  GNU
CC does not support all possible alternatives.

   Often a particular model of machine has a name.  Many machine names
are recognized as aliases for CPU/company combinations.  Thus, the
machine name `sun3', mentioned above, is an alias for `m68k-sun'.
Sometimes we accept a company name as a machine name, when the name is
popularly used for a particular machine.  Here is a table of the known
machine names:

     3300, 3b1, 3bN, 7300, altos3068, altos, apollo68, att-7300,
     balance, convex-cN, crds, decstation-3100, decstation, delta,
     encore, fx2800, gmicro, hp7NN, hp8NN, hp9k2NN, hp9k3NN, hp9k7NN,
     hp9k8NN, iris4d, iris, isi68, m3230, magnum, merlin, miniframe,
     mmax, news-3600, news800, news, next, pbd, pc532, pmax, powerpc,
     powerpcle, ps2, risc-news, rtpc, sun2, sun386i, sun386, sun3,
     sun4, symmetry, tower-32, tower.

Remember that a machine name specifies both the cpu type and the company
name.  If you want to install your own homemade configuration files,
you can use `local' as the company name to access them.  If you use
configuration `CPU-local', the configuration name without the cpu prefix
is used to form the configuration file names.

   Thus, if you specify `m68k-local', configuration uses files
`m68k.md', `local.h', `m68k.c', `xm-local.h', `t-local', and `x-local',
all in the directory `config/m68k'.

   Here is a list of configurations that have special treatment or
special things you must know:

`1750a-*-*'
     MIL-STD-1750A processors.

     Starting with GCC 2.6.1, the MIL-STD-1750A cross configuration no
     longer supports the Tektronix Assembler, but instead produces
     output for `as1750', an assembler/linker available under the GNU
     Public License for the 1750A. Contact *kellogg@space.otn.dasa.de*
     for more details on obtaining `as1750'.  A similarly licensed
     simulator for the 1750A is available from same address.

     You should ignore a fatal error during the building of libgcc
     (libgcc is not yet implemented for the 1750A.)

     The `as1750' assembler requires the file `ms1750.inc', which is
     found in the directory `config/1750a'.

     GNU CC produced the same sections as the Fairchild F9450 C
     Compiler, namely:

    `Normal'
          The program code section.

    `Static'
          The read/write (RAM) data section.

    `Konst'
          The read-only (ROM) constants section.

    `Init'
          Initialization section (code to copy KREL to SREL).

     The smallest addressable unit is 16 bits (BITS_PER_UNIT is 16).
     This means that type `char' is represented with a 16-bit word per
     character.  The 1750A's "Load/Store Upper/Lower Byte" instructions
     are not used by GNU CC.

`alpha-*-osf1'
     Systems using processors that implement the DEC Alpha architecture
     and are running the DEC Unix (OSF/1) operating system, for example
     the DEC Alpha AXP systems.  (VMS on the Alpha is not currently
     supported by GNU CC.)

     GNU CC writes a `.verstamp' directive to the assembler output file
     unless it is built as a cross-compiler.  It gets the version to
     use from the system header file `/usr/include/stamp.h'.  If you
     install a new version of DEC Unix, you should rebuild GCC to pick
     up the new version stamp.

     Note that since the Alpha is a 64-bit architecture,
     cross-compilers from 32-bit machines will not generate code as
     efficient as that generated when the compiler is running on a
     64-bit machine because many optimizations that depend on being
     able to represent a word on the target in an integral value on the
     host cannot be performed.  Building cross-compilers on the Alpha
     for 32-bit machines has only been tested in a few cases and may
     not work properly.

     `make compare' may fail on old versions of DEC Unix unless you add
     `-save-temps' to `CFLAGS'.  On these systems, the name of the
     assembler input file is stored in the object file, and that makes
     comparison fail if it differs between the `stage1' and `stage2'
     compilations.  The option `-save-temps' forces a fixed name to be
     used for the assembler input file, instead of a randomly chosen
     name in `/tmp'.  Do not add `-save-temps' unless the comparisons
     fail without that option.  If you add `-save-temps', you will have
     to manually delete the `.i' and `.s' files after each series of
     compilations.

     GNU CC now supports both the native (ECOFF) debugging format used
     by DBX and GDB and an encapsulated STABS format for use only with
     GDB.  See the discussion of the `--with-stabs' option of
     `configure' above for more information on these formats and how to
     select them.

     There is a bug in DEC's assembler that produces incorrect line
     numbers for ECOFF format when the `.align' directive is used.  To
     work around this problem, GNU CC will not emit such alignment
     directives while writing ECOFF format debugging information even
     if optimization is being performed.  Unfortunately, this has the
     very undesirable side-effect that code addresses when `-O' is
     specified are different depending on whether or not `-g' is also
     specified.

     To avoid this behavior, specify `-gstabs+' and use GDB instead of
     DBX.  DEC is now aware of this problem with the assembler and
     hopes to provide a fix shortly.

`arm'
     Advanced RISC Machines ARM-family processors.  These are often
     used in embedded applications.  There are no standard Unix
     configurations.  This configuration corresponds to the basic
     instruction sequences and will produce a.out format object modules.

     You may need to make a variant of the file `arm.h' for your
     particular configuration.

`arm-*-riscix'
     The ARM2 or ARM3 processor running RISC iX, Acorn's port of BSD
     Unix.  If you are running a version of RISC iX prior to 1.2 then
     you must specify the version number during configuration.  Note
     that the assembler shipped with RISC iX does not support stabs
     debugging information; a new version of the assembler, with stabs
     support included, is now available from Acorn.

`a29k'
     AMD Am29k-family processors.  These are normally used in embedded
     applications.  There are no standard Unix configurations.  This
     configuration corresponds to AMD's standard calling sequence and
     binary interface and is compatible with other 29k tools.

     You may need to make a variant of the file `a29k.h' for your
     particular configuration.

`a29k-*-bsd'
     AMD Am29050 used in a system running a variant of BSD Unix.

`decstation-*'
     DECstations can support three different personalities: Ultrix, DEC
     OSF/1, and OSF/rose.  To configure GCC for these platforms use the
     following configurations:

    `decstation-ultrix'
          Ultrix configuration.

    `decstation-osf1'
          Dec's version of OSF/1.

    `decstation-osfrose'
          Open Software Foundation reference port of OSF/1 which uses
          the OSF/rose object file format instead of ECOFF.  Normally,
          you would not select this configuration.

     The MIPS C compiler needs to be told to increase its table size
     for switch statements with the `-Wf,-XNg1500' option in order to
     compile `cp/parse.c'.  If you use the `-O2' optimization option,
     you also need to use `-Olimit 3000'.  Both of these options are
     automatically generated in the `Makefile' that the shell script
     `configure' builds.  If you override the `CC' make variable and
     use the MIPS compilers, you may need to add `-Wf,-XNg1500 -Olimit
     3000'.

`elxsi-elxsi-bsd'
     The Elxsi's C compiler has known limitations that prevent it from
     compiling GNU C.  Please contact `mrs@cygnus.com' for more details.

`dsp16xx'
     A port to the AT&T DSP1610 family of processors.

`h8300-*-*'
     The calling convention and structure layout has changed in release
     2.6.  All code must be recompiled.  The calling convention now
     passes the first three arguments in function calls in registers.
     Structures are no longer a multiple of 2 bytes.

`hppa*-*-*'
     There are several variants of the HP-PA processor which run a
     variety of operating systems.  GNU CC must be configured to use
     the correct processor type and operating system, or GNU CC will
     not function correctly.  The easiest way to handle this problem is
     to *not* specify a target when configuring GNU CC, the `configure'
     script will try to automatically determine the right processor
     type and operating system.

     `-g' does not work on HP-UX, since that system uses a peculiar
     debugging format which GNU CC does not know about.  However, `-g'
     will work if you also use GAS and GDB in conjunction with GCC.  We
     highly recommend using GAS for all HP-PA configurations.

     You should be using GAS-2.6 (or later) along with GDB-4.16 (or
     later).  These can be retrieved from all the traditional GNU ftp
     archive sites.

     GAS will need to be installed into a directory before `/bin',
     `/usr/bin', and `/usr/ccs/bin' in your search path.  You should
     install GAS before you build GNU CC.

     To enable debugging, you must configure GNU CC with the
     `--with-gnu-as' option before building.

`i370-*-*'
     This port is very preliminary and has many known bugs.  We hope to
     have a higher-quality port for this machine soon.

`i386-*-linuxoldld'
     Use this configuration to generate a.out binaries on Linux-based
     GNU systems, if you do not have gas/binutils version 2.5.2 or later
     installed.  This is an obsolete configuration.

`i386-*-linuxaout'
     Use this configuration to generate a.out binaries on Linux-based
     GNU systems.  This configuration is being superseded.  You must use
     gas/binutils version 2.5.2 or later.

`i386-*-linux'
     Use this configuration to generate ELF binaries on Linux-based GNU
     systems.  You must use gas/binutils version 2.5.2 or later.

`i386-*-sco'
     Compilation with RCC is recommended.  Also, it may be a good idea
     to link with GNU malloc instead of the malloc that comes with the
     system.

`i386-*-sco3.2v4'
     Use this configuration for SCO release 3.2 version 4.

`i386-*-isc'
     It may be a good idea to link with GNU malloc instead of the
     malloc that comes with the system.

     In ISC version 4.1, `sed' core dumps when building `deduced.h'.
     Use the version of `sed' from version 4.0.

`i386-*-esix'
     It may be good idea to link with GNU malloc instead of the malloc
     that comes with the system.

`i386-ibm-aix'
     You need to use GAS version 2.1 or later, and and LD from GNU
     binutils version 2.2 or later.

`i386-sequent-bsd'
     Go to the Berkeley universe before compiling.  In addition, you
     probably need to create a file named `string.h' containing just
     one line: `#include <strings.h>'.

`i386-sequent-ptx1*'
     Sequent DYNIX/ptx 1.x.

`i386-sequent-ptx2*'
     Sequent DYNIX/ptx 2.x.

`i386-sun-sunos4'
     You may find that you need another version of GNU CC to begin
     bootstrapping with, since the current version when built with the
     system's own compiler seems to get an infinite loop compiling part
     of `libgcc2.c'.  GNU CC version 2 compiled with GNU CC (any
     version) seems not to have this problem.

     See Note: Sun Install, for information on installing GNU CC on
     Sun systems.

`i[345]86-*-winnt3.5'
     This version requires a GAS that has not let been released.  Until
     it is, you can get a prebuilt binary version via anonymous ftp from
     `cs.washington.edu:pub/gnat' or `cs.nyu.edu:pub/gnat'. You must
     also use the Microsoft header files from the Windows NT 3.5 SDK.
     Find these on the CDROM in the `/mstools/h' directory dated
     9/4/94.  You must use a fixed version of Microsoft linker made
     especially for NT 3.5, which is also is available on the NT 3.5
     SDK CDROM.  If you do not have this linker, can you also use the
     linker from Visual C/C++ 1.0 or 2.0.

     Installing GNU CC for NT builds a wrapper linker, called `ld.exe',
     which mimics the behaviour of Unix `ld' in the specification of
     libraries (`-L' and `-l').  `ld.exe' looks for both Unix and
     Microsoft named libraries.  For example, if you specify `-lfoo',
     `ld.exe' will look first for `libfoo.a' and then for `foo.lib'.

     You may install GNU CC for Windows NT in one of two ways,
     depending on whether or not you have a Unix-like shell and various
     Unix-like utilities.

       1. If you do not have a Unix-like shell and few Unix-like
          utilities, you will use a DOS style batch script called
          `configure.bat'.  Invoke it as `configure winnt' from an
          MSDOS console window or from the program manager dialog box.
          `configure.bat' assumes you have already installed and have
          in your path a Unix-like `sed' program which is used to
          create a working `Makefile' from `Makefile.in'.

          `Makefile' uses the Microsoft Nmake program maintenance
          utility and the Visual C/C++ V8.00 compiler to build GNU CC.
          You need only have the utilities `sed' and `touch' to use
          this installation method, which only automatically builds the
          compiler itself.  You must then examine what `fixinc.winnt'
          does, edit the header files by hand and build `libgcc.a'
          manually.

       2. The second type of installation assumes you are running a
          Unix-like shell, have a complete suite of Unix-like utilities
          in your path, and have a previous version of GNU CC already
          installed, either through building it via the above
          installation method or acquiring a pre-built binary.  In this
          case, use the `configure' script in the normal fashion.

`i860-intel-osf1'
     This is the Paragon.  If you have version 1.0 of the operating
     system, see Note: Installation Problems, for special things you
     need to do to compensate for peculiarities in the system.

`*-lynx-lynxos'
     LynxOS 2.2 and earlier comes with GNU CC 1.x already installed as
     `/bin/gcc'.  You should compile with this instead of `/bin/cc'.
     You can tell GNU CC to use the GNU assembler and linker, by
     specifying `--with-gnu-as --with-gnu-ld' when configuring.  These
     will produce COFF format object files and executables;  otherwise
     GNU CC will use the installed tools, which produce a.out format
     executables.

`m68000-hp-bsd'
     HP 9000 series 200 running BSD.  Note that the C compiler that
     comes with this system cannot compile GNU CC; contact
     `law@cs.utah.edu' to get binaries of GNU CC for bootstrapping.

`m68k-altos'
     Altos 3068.  You must use the GNU assembler, linker and debugger.
     Also, you must fix a kernel bug.  Details in the file
     `README.ALTOS'.

`m68k-att-sysv'
     AT&T 3b1, a.k.a. 7300 PC.  Special procedures are needed to
     compile GNU CC with this machine's standard C compiler, due to
     bugs in that compiler.  You can bootstrap it more easily with
     previous versions of GNU CC if you have them.

     Installing GNU CC on the 3b1 is difficult if you do not already
     have GNU CC running, due to bugs in the installed C compiler.
     However, the following procedure might work.  We are unable to
     test it.

       1. Comment out the `#include "config.h"' line on line 37 of
          `cccp.c' and do `make cpp'.  This makes a preliminary version
          of GNU cpp.

       2. Save the old `/lib/cpp' and copy the preliminary GNU cpp to
          that file name.

       3. Undo your change in `cccp.c', or reinstall the original
          version, and do `make cpp' again.

       4. Copy this final version of GNU cpp into `/lib/cpp'.

       5. Replace every occurrence of `obstack_free' in the file
          `tree.c' with `_obstack_free'.

       6. Run `make' to get the first-stage GNU CC.

       7. Reinstall the original version of `/lib/cpp'.

       8. Now you can compile GNU CC with itself and install it in the
          normal fashion.

`m68k-bull-sysv'
     Bull DPX/2 series 200 and 300 with BOS-2.00.45 up to BOS-2.01. GNU
     CC works either with native assembler or GNU assembler. You can use
     GNU assembler with native coff generation by providing
     `--with-gnu-as' to the configure script or use GNU assembler with
     dbx-in-coff encapsulation by providing `--with-gnu-as --stabs'.
     For any problem with native assembler or for availability of the
     DPX/2 port of GAS, contact `F.Pierresteguy@frcl.bull.fr'.

`m68k-crds-unox'
     Use `configure unos' for building on Unos.

     The Unos assembler is named `casm' instead of `as'.  For some
     strange reason linking `/bin/as' to `/bin/casm' changes the
     behavior, and does not work.  So, when installing GNU CC, you
     should install the following script as `as' in the subdirectory
     where the passes of GCC are installed:

          #!/bin/sh
          casm $*

     The default Unos library is named `libunos.a' instead of `libc.a'.
     To allow GNU CC to function, either change all references to
     `-lc' in `gcc.c' to `-lunos' or link `/lib/libc.a' to
     `/lib/libunos.a'.

     When compiling GNU CC with the standard compiler, to overcome bugs
     in the support of `alloca', do not use `-O' when making stage 2.
     Then use the stage 2 compiler with `-O' to make the stage 3
     compiler.  This compiler will have the same characteristics as the
     usual stage 2 compiler on other systems.  Use it to make a stage 4
     compiler and compare that with stage 3 to verify proper
     compilation.

     (Perhaps simply defining `ALLOCA' in `x-crds' as described in the
     comments there will make the above paragraph superfluous.  Please
     inform us of whether this works.)

     Unos uses memory segmentation instead of demand paging, so you
     will need a lot of memory.  5 Mb is barely enough if no other
     tasks are running.  If linking `cc1' fails, try putting the object
     files into a library and linking from that library.

`m68k-hp-hpux'
     HP 9000 series 300 or 400 running HP-UX.  HP-UX version 8.0 has a
     bug in the assembler that prevents compilation of GNU CC.  To fix
     it, get patch PHCO_4484 from HP.

     In addition, if you wish to use gas `--with-gnu-as' you must use
     gas version 2.1 or later, and you must use the GNU linker version
     2.1 or later.  Earlier versions of gas relied upon a program which
     converted the gas output into the native HP/UX format, but that
     program has not been kept up to date.  gdb does not understand
     that native HP/UX format, so you must use gas if you wish to use
     gdb.

`m68k-sun'
     Sun 3.  We do not provide a configuration file to use the Sun FPA
     by default, because programs that establish signal handlers for
     floating point traps inherently cannot work with the FPA.

     See Note: Sun Install, for information on installing GNU CC on
     Sun systems.

`m88k-*-svr3'
     Motorola m88k running the AT&T/Unisoft/Motorola V.3 reference port.
     These systems tend to use the Green Hills C, revision 1.8.5, as the
     standard C compiler.  There are apparently bugs in this compiler
     that result in object files differences between stage 2 and stage
     3.  If this happens, make the stage 4 compiler and compare it to
     the stage 3 compiler.  If the stage 3 and stage 4 object files are
     identical, this suggests you encountered a problem with the
     standard C compiler; the stage 3 and 4 compilers may be usable.

     It is best, however, to use an older version of GNU CC for
     bootstrapping if you have one.

`m88k-*-dgux'
     Motorola m88k running DG/UX.  To build 88open BCS native or cross
     compilers on DG/UX, specify the configuration name as
     `m88k-*-dguxbcs' and build in the 88open BCS software development
     environment.  To build ELF native or cross compilers on DG/UX,
     specify `m88k-*-dgux' and build in the DG/UX ELF development
     environment.  You set the software development environment by
     issuing `sde-target' command and specifying either `m88kbcs' or
     `m88kdguxelf' as the operand.

     If you do not specify a configuration name, `configure' guesses the
     configuration based on the current software development
     environment.

`m88k-tektronix-sysv3'
     Tektronix XD88 running UTekV 3.2e.  Do not turn on optimization
     while building stage1 if you bootstrap with the buggy Green Hills
     compiler.  Also, The bundled LAI System V NFS is buggy so if you
     build in an NFS mounted directory, start from a fresh reboot, or
     avoid NFS all together.  Otherwise you may have trouble getting
     clean comparisons between stages.

`mips-mips-bsd'
     MIPS machines running the MIPS operating system in BSD mode.  It's
     possible that some old versions of the system lack the functions
     `memcpy', `memcmp', and `memset'.  If your system lacks these, you
     must remove or undo the definition of `TARGET_MEM_FUNCTIONS' in
     `mips-bsd.h'.

     The MIPS C compiler needs to be told to increase its table size
     for switch statements with the `-Wf,-XNg1500' option in order to
     compile `cp/parse.c'.  If you use the `-O2' optimization option,
     you also need to use `-Olimit 3000'.  Both of these options are
     automatically generated in the `Makefile' that the shell script
     `configure' builds.  If you override the `CC' make variable and
     use the MIPS compilers, you may need to add `-Wf,-XNg1500 -Olimit
     3000'.

`mips-mips-riscos*'
     The MIPS C compiler needs to be told to increase its table size
     for switch statements with the `-Wf,-XNg1500' option in order to
     compile `cp/parse.c'.  If you use the `-O2' optimization option,
     you also need to use `-Olimit 3000'.  Both of these options are
     automatically generated in the `Makefile' that the shell script
     `configure' builds.  If you override the `CC' make variable and
     use the MIPS compilers, you may need to add `-Wf,-XNg1500 -Olimit
     3000'.

     MIPS computers running RISC-OS can support four different
     personalities: default, BSD 4.3, System V.3, and System V.4 (older
     versions of RISC-OS don't support V.4).  To configure GCC for
     these platforms use the following configurations:

    `mips-mips-riscos`rev''
          Default configuration for RISC-OS, revision `rev'.

    `mips-mips-riscos`rev'bsd'
          BSD 4.3 configuration for RISC-OS, revision `rev'.

    `mips-mips-riscos`rev'sysv4'
          System V.4 configuration for RISC-OS, revision `rev'.

    `mips-mips-riscos`rev'sysv'
          System V.3 configuration for RISC-OS, revision `rev'.

     The revision `rev' mentioned above is the revision of RISC-OS to
     use.  You must reconfigure GCC when going from a RISC-OS revision
     4 to RISC-OS revision 5.  This has the effect of avoiding a linker
     bug (see Note: Installation Problems, for more details).

`mips-sgi-*'
     In order to compile GCC on an SGI running IRIX 4, the "c.hdr.lib"
     option must be installed from the CD-ROM supplied from Silicon
     Graphics.  This is found on the 2nd CD in release 4.0.1.

     In order to compile GCC on an SGI running IRIX 5, the
     "compiler_dev.hdr" subsystem must be installed from the IDO CD-ROM
     supplied by Silicon Graphics.

     `make compare' may fail on version 5 of IRIX unless you add
     `-save-temps' to `CFLAGS'.  On these systems, the name of the
     assembler input file is stored in the object file, and that makes
     comparison fail if it differs between the `stage1' and `stage2'
     compilations.  The option `-save-temps' forces a fixed name to be
     used for the assembler input file, instead of a randomly chosen
     name in `/tmp'.  Do not add `-save-temps' unless the comparisons
     fail without that option.  If you do you `-save-temps', you will
     have to manually delete the `.i' and `.s' files after each series
     of compilations.

     The MIPS C compiler needs to be told to increase its table size
     for switch statements with the `-Wf,-XNg1500' option in order to
     compile `cp/parse.c'.  If you use the `-O2' optimization option,
     you also need to use `-Olimit 3000'.  Both of these options are
     automatically generated in the `Makefile' that the shell script
     `configure' builds.  If you override the `CC' make variable and
     use the MIPS compilers, you may need to add `-Wf,-XNg1500 -Olimit
     3000'.

     On Irix version 4.0.5F, and perhaps on some other versions as well,
     there is an assembler bug that reorders instructions incorrectly.
     To work around it, specify the target configuration
     `mips-sgi-irix4loser'.  This configuration inhibits assembler
     optimization.

     In a compiler configured with target `mips-sgi-irix4', you can turn
     off assembler optimization by using the `-noasmopt' option.  This
     compiler option passes the option `-O0' to the assembler, to
     inhibit reordering.

     The `-noasmopt' option can be useful for testing whether a problem
     is due to erroneous assembler reordering.  Even if a problem does
     not go away with `-noasmopt', it may still be due to assembler
     reordering--perhaps GNU CC itself was miscompiled as a result.

     To enable debugging under Irix 5, you must use GNU as 2.5 or later,
     and use the `--with-gnu-as' configure option when configuring gcc.
     GNU as is distributed as part of the binutils package.

`mips-sony-sysv'
     Sony MIPS NEWS.  This works in NEWSOS 5.0.1, but not in 5.0.2
     (which uses ELF instead of COFF).  Support for 5.0.2 will probably
     be provided soon by volunteers.  In particular, the linker does
     not like the code generated by GCC when shared libraries are
     linked in.

`ns32k-encore'
     Encore ns32000 system.  Encore systems are supported only under
     BSD.

`ns32k-*-genix'
     National Semiconductor ns32000 system.  Genix has bugs in `alloca'
     and `malloc'; you must get the compiled versions of these from GNU
     Emacs.

`ns32k-sequent'
     Go to the Berkeley universe before compiling.  In addition, you
     probably need to create a file named `string.h' containing just
     one line: `#include <strings.h>'.

`ns32k-utek'
     UTEK ns32000 system ("merlin").  The C compiler that comes with
     this system cannot compile GNU CC; contact `tektronix!reed!mason'
     to get binaries of GNU CC for bootstrapping.

`romp-*-aos'
`romp-*-mach'
     The only operating systems supported for the IBM RT PC are AOS and
     MACH.  GNU CC does not support AIX running on the RT.  We
     recommend you compile GNU CC with an earlier version of itself; if
     you compile GNU CC with `hc', the Metaware compiler, it will work,
     but you will get mismatches between the stage 2 and stage 3
     compilers in various files.  These errors are minor differences in
     some floating-point constants and can be safely ignored; the stage
     3 compiler is correct.

`rs6000-*-aix'
`powerpc-*-aix'
     Various early versions of each release of the IBM XLC compiler
     will not bootstrap GNU CC.  Symptoms include differences between
     the stage2 and stage3 object files, and errors when compiling
     `libgcc.a' or `enquire'.  Known problematic releases include:
     xlc-1.2.1.8, xlc-1.3.0.0 (distributed with AIX 3.2.5), and
     xlc-1.3.0.19.  Both xlc-1.2.1.28 and xlc-1.3.0.24 (PTF 432238) are
     known to produce working versions of GNU CC, but most other recent
     releases correctly bootstrap GNU CC.  Also, releases of AIX prior
     to AIX 3.2.4 include a version of the IBM assembler which does not
     accept debugging directives: assembler updates are available as
     PTFs.  Also, if you are using AIX 3.2.5 or greater and the GNU
     assembler, you must have a version modified after October 16th,
     1995 in order for the GNU C compiler to build.  See the file
     `README.RS6000' for more details on of these problems.

     GNU CC does not yet support the 64-bit PowerPC instructions.

     Objective C does not work on this architecture because it makes
     assumptions that are incompatible with the calling conventions.

     AIX on the RS/6000 provides support (NLS) for environments outside
     of the United States.  Compilers and assemblers use NLS to support
     locale-specific representations of various objects including
     floating-point numbers ("." vs "," for separating decimal
     fractions).  There have been problems reported where the library
     linked with GNU CC does not produce the same floating-point
     formats that the assembler accepts.  If you have this problem, set
     the LANG environment variable to "C" or "En_US".

     Due to changes in the way that GNU CC invokes the binder (linker)
     for AIX 4.1, you may now receive warnings of duplicate symbols
     from the link step that were not reported before.  The assembly
     files generated by GNU CC for AIX have always included multiple
     symbol definitions for certain global variable and function
     declarations in the original program.  The warnings should not
     prevent the linker from producing a correct library or runnable
     executable.

`powerpc-*-elf'
`powerpc-*-sysv4'
     PowerPC system in big endian mode, running System V.4.

     This configuration is currently under development.

`powerpc-*-eabiaix'
     Embedded PowerPC system in big endian mode with -mcall-aix
     selected as the default.  This system is currently under
     development.

`powerpc-*-eabisim'
     Embedded PowerPC system in big endian mode for use in running
     under the PSIM simulator.  This system is currently under
     development.

`powerpc-*-eabi'
     Embedded PowerPC system in big endian mode.

     This configuration is currently under development.

`powerpcle-*-elf'
`powerpcle-*-sysv4'
     PowerPC system in little endian mode, running System V.4.

     This configuration is currently under development.

`powerpcle-*-sysv4'
     Embedded PowerPC system in little endian mode.

     This system is currently under development.

`powerpcle-*-eabisim'
     Embedded PowerPC system in little endian mode for use in running
     under the PSIM simulator.

     This system is currently under development.

`powerpcle-*-eabi'
     Embedded PowerPC system in little endian mode.

     This configuration is currently under development.

`vax-dec-ultrix'
     Don't try compiling with Vax C (`vcc').  It produces incorrect code
     in some cases (for example, when `alloca' is used).

     Meanwhile, compiling `cp/parse.c' with pcc does not work because of
     an internal table size limitation in that compiler.  To avoid this
     problem, compile just the GNU C compiler first, and use it to
     recompile building all the languages that you want to run.

`sparc-sun-*'
     See Note: Sun Install, for information on installing GNU CC on
     Sun systems.

`vax-dec-vms'
     See Note: VMS Install, for details on how to install GNU CC on
     VMS.

`we32k-*-*'
     These computers are also known as the 3b2, 3b5, 3b20 and other
     similar names.  (However, the 3b1 is actually a 68000; see Note:
     Configurations.)

     Don't use `-g' when compiling with the system's compiler.  The
     system's linker seems to be unable to handle such a large program
     with debugging information.

     The system's compiler runs out of capacity when compiling `stmt.c'
     in GNU CC.  You can work around this by building `cpp' in GNU CC
     first, then use that instead of the system's preprocessor with the
     system's C compiler to compile `stmt.c'.  Here is how:

          mv /lib/cpp /lib/cpp.att
          cp cpp /lib/cpp.gnu
          echo '/lib/cpp.gnu -traditional ${1+"$@"}' > /lib/cpp
          chmod +x /lib/cpp

     The system's compiler produces bad code for some of the GNU CC
     optimization files.  So you must build the stage 2 compiler without
     optimization.  Then build a stage 3 compiler with optimization.
     That executable should work.  Here are the necessary commands:

          make LANGUAGES=c CC=stage1/xgcc CFLAGS="-Bstage1/ -g"
          make stage2
          make CC=stage2/xgcc CFLAGS="-Bstage2/ -g -O"

     You may need to raise the ULIMIT setting to build a C++ compiler,
     as the file `cc1plus' is larger than one megabyte.


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