The following 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.

acorn, alliant, altos, apollo, apple, 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 following is a list of system types:

386bsd, aix, acis, amigados, aos, aout, aux, 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 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 previously, 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.

The following are the known machine names:

3300, 3b1, 3b n, 7300, altos3068, altos, apollo68, att-7300, balance, convex-c n, crds, decstation-3100, decstation, delta, encore, fx2800, gmicro, hp7 nn, 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.

What follows 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 the 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:

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. That is 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 Installing GNU CC for a discussion of the ‘--with-stabs’ option of configure 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 in-stead of DBX. DEC is now aware of this problem with the assembler and hopes to provide a fix shortly. See Options for debugging your program or GNU CC.
arc-*-elf
Argonaut ARC processor. This configuration is intended for embedded systems.
 
arm-*-aout
Advanced RISC Machines ARM-family processors. These are often used in embedded applications. There are no standard Unix con gurations. 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 particuar configuration.
 
arm-*-linuxaout
Any of the ARM family processors running the Linux-based GNU system with the a.out binary format (ELF is not yet supported). You must use version 2.8.1.0.7 or later of the GNU/Linux binutils, which you can download from sunsite.unc.edu:/pub/Linux/GCC, and other mirror sites for Linux-based GNU systems.
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:

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 for-mat 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 avoid specifying 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 HPUX, since that system uses a peculiar debugging format about which GNU CC does not know. However, ‘-g’ will work if you also use GAS and GDB in conjunction with GCC. We highly recommend using GAS for all HPPA 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. Install GAS into a directory before /bin, /usr/bin, and /usr/ccs/bin in your search path.
To enable debugging, 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-*-linux-gnuoldld
Use this configuration to generate ‘a.out’ binaries on Linux if you do not have gas/binutils version 2.5.2 or later installed. This is an obsolete configuration.
i386-*-linux-gnuaout
Use this configuration to generate ‘a.out’ binaries on Linux. This configuration is being superseded. You must use gas/binutils version 2.5.2 or later.
i386-*-linux-gnu
Use this configuration to generate ELF binaries on Linux. 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 4.0.
i386-*-sco3.2v5
Use this for SCO Open Server release 3.2 version 5.0. GNU CC can generate ELF binaries (if you specify ‘-melf’) or COFF binaries (the default). If you are going to build your compiler in ELF mode (once you have bootstrapped the first stage compiler) you must specify ‘-melf’ as part of CC, not CFLAGS.
You should use some variant of: CC="stage1/xgcc -melf" CFLAGS="-Bstage1/". If you do not do this, the bootstrap will generate completely bogus versions of libgcc.a. You must have TLS597 (from ftp.sco.com/TLS) installed for ELF binaries to work correctly.
Note:

Open Server 5.0.2 does need TLS597 installed.
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 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’ using #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 Installing GNU CC on the Sun 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 pre-built 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 September 4, 1994. 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 behavior 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.
• 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 pro-gram 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 only need 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.
• 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 previous 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 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 /bin/gcc instead of /bin/cc. You can tell GNU CC to use the GNU assembler and linker, by specifying the ‘--with-gnu-as’ and ‘--with-gnu-ld’ options 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.
m32r-*-elf
Mitsubishi M32R processor. This configuration is intended for embedded systems.
m68000-hp-bsd
HP 9000 series 200 running BSD.
Note:

The C compiler that comes with this system cannot compile GNUCC; 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-apple-aux
Apple Macintosh running A/UX. You may configure GCC to use either the system assembler and linker or the GNU assembler and linker.
You should use the GNU configuration if you can, especially if you also want to use GNU C++. You enabled that configuration with the ‘--with-gnu-as’ and ‘--with-gnu-ld’ options to configure.
Note:
The C compiler that comes with this system cannot compile GNU CC. You can fine binaries of GNU CC for bootstrapping on jagubox.gsfc.nasa.gov. There is also a patched version of ‘/bin/ld’ there that raises some of the arbitrary limits found in the original.
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 ‘#include "config.h"’ 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 filename.
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 BOS2.00.45 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.
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 HPUX. HPUX 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 the gas function ‘--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 Installing GNU CC on the  Sun 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-riscosrev

Default configuration for RISC-OS, revision rev.
• mips-mips-riscosrevbsd

BSD 4.3 configuration for RISC-OS, revision rev.
• mips-mips-riscosrevsysv4

System V.4 configuration for RISC-OS, revision rev.
• mips-mips-riscosrevsysv

System V.3 configuration for RISC-OS, revision rev.
The revision, rev (mentioned in the previous paragraphs), 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 Installation Problems).
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 second 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 by the IDO CD-ROM, supplied by Silicon Graphics.
make compare may fail on version 5 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 ‘mips-sgi-irix4loser’ as the target configuration. 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 16, 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 all 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. By default, AIX 4.1 produces code that can be used on either Power or PowerPC processors. You can specify a default version for the ‘-mcpu=’ cpu_type switch by using the configure option, ‘—with-cpu-’ cpu_type.
powerpc-*-elf
powerpc-*-sysv4
PowerPC system in big endian mode, running System V.4. You can specify a default version for the ‘-mcpu=’cpu_type switch using the option, ‘--with-cpu-’ cpu_type.
powerpc-*-linux-gnu
PowerPC system in big endian mode, running the Linux-based GNU system. You can specify a default version for the ‘-mcpu=’cpu_type switch using the option, ‘--with-cpu-’ cpu_type.
powerpc-*-eabiaix
Embedded PowerPC system in big endian mode with ‘-mcall-aix’ selected as the default. You can specify a default version for the ‘-mcpu=’ cpu_type switch by using the configure option, ‘--with-cpu-’ cpu_type.
powerpc-*-eabisim
Embedded PowerPC system in big endian mode for use in running under the PSIM simulator. You can specify a default version for the ‘-mcpu=’ cpu_type switch by using the configure option, ‘--with-cpu-’ cpu_type.
powerpc-*-eabi
Embedded PowerPC system in big endian mode. You can specify a default version for the ‘-mcpu=’cpu_type switch by using the configure option,‘--with-cpu-’cpu_type.
powerpcle-*-elf
powerpcle-*-sysv4
PowerPC system in little endian mode, running System V.4. You can specify a default version for the ‘-mcpu=’cpu_type switch using the option, ‘--with-cpu-’ cpu_type.
powerpcle-*-solaris2*
PowerPC system in little endian mode for use in running Solaris 2.5.1 or higher.
You can specify a default version for the ‘-mcpu=’ cpu_type switch by using the configure option, ‘--with-cpu-’ cpu_type. Beta versions of the Sun 4.0 compiler do not seem to be able to build GNU CC correctly. There are also problems with the host assembler and linker that are fixed by using the GNU versions of these tools.
powerpcle-*-eabi
Embedded PowerPC system in little endian mode. You can specify a default version for the ‘-mcpu=’ cpu_type switch by using the option, ‘—with-cpu-’ cpu_type.
powerpcle-*-winnt
powerpcle-*-pe
PowerPC system in little endian mode running Windows NT. You can specify a default version for the ‘-mcpu=’ cpu_type switch by using the configure option, ‘—with-cpu-’ cpu_type.
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-*’
sparc64-sun-*
See Installing GNU CC on the Sun for information on installing GNU CC on Sun systems.
vax-dec-vms
See Installing GNU CC on VMS 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.) 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’. Use the following example’s input.

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. Use the following.

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.