# Host/Target specific installation notes for GCC

Please read this document carefully before installing the GNU Compiler Collection on your machine.

- alpha*-*-*
- alpha*-dec-osf*
- alphaev5-cray-unicosmk*
- arc-*-elf
- arm-*-aout
- arm-*-elf
- arm*-*-linux-gnu
- avr
- c4x
- DOS
- dsp16xx
- *-*-freebsd*
- h8300-hms
- hppa*-hp-hpux*
- hppa*-hp-hpux9
- hppa*-hp-hpux10
- hppa*-hp-hpux11
- i370-*-*
- *-*-linux-gnu
- i?86-*-linux*aout
- i?86-*-linux*
- i?86-*-sco
- i?86-*-sco3.2v4
- i?86-*-sco3.2v5*
- i?86-*-udk
- i?86-*-esix
- ia64-*-linux
- ia64-*-hpux*
- *-lynx-lynxos
- *-ibm-aix*
- ip2k-*-elf
- m32r-*-elf
- m68000-hp-bsd
- m6811-elf
- m6812-elf
- m68k-att-sysv
- m68k-crds-unos
- m68k-hp-hpux
- m68k-ncr-*
- m68k-sun
- m68k-sun-sunos4.1.1
- mips-*-*
- mips-sgi-irix5
- mips-sgi-irix6
- powerpc*-*-* powerpc-*-sysv4
- powerpc-*-darwin*
- powerpc-*-elf powerpc-*-sysv4
- powerpc-*-linux-gnu*
- powerpc-*-netbsd*
- powerpc-*-eabiaix
- powerpc-*-eabisim
- powerpc-*-eabi
- powerpcle-*-elf powerpcle-*-sysv4
- powerpcle-*-eabisim
- powerpcle-*-eabi
- s390-*-linux*
- s390x-*-linux*
- *-*-solaris2*
- sparc-sun-solaris2*
- sparc-sun-solaris2.7
- sparc-sun-sunos4*
- sparc-unknown-linux-gnulibc1
- sparc-*-linux*
- sparc64-*-solaris2*
- sparcv9-*-solaris2*
- *-*-sysv*
- vax-dec-ultrix
- xtensa-*-elf
- xtensa-*-linux*
- Microsoft Windows
- OS/2
- Older systems

- all ELF targets (SVR4, Solaris 2, etc.)

### alpha*-*-*

This section contains general configuration information for all alpha-based platforms using ELF (in particular, ignore this section for DEC OSF/1, Digital UNIX and Tru64 UNIX). In addition to reading this section, please read all other sections that match your target.

We require binutils 2.11.2 or newer. Previous binutils releases had a number of problems with DWARF 2 debugging information, not the least of which is incorrect linking of shared libraries.

### alpha*-dec-osf*

Systems using processors that implement the DEC Alpha architecture and are running the DEC/Compaq Unix (DEC OSF/1, Digital UNIX, or Compaq Tru64 UNIX) operating system, for example the DEC Alpha AXP systems.

As of GCC 3.2, versions before `alpha*-dec-osf4` are no longer supported. (These are the versions which identify themselves as DEC OSF/1.)

In Digital Unix V4.0, virtual memory exhausted bootstrap failures may be fixed by configuring with `--with-gc=simple`, reconfiguring Kernel Virtual Memory and Swap parameters per the `/usr/sbin/sys_check` Tuning Suggestions, or applying the patch in http://gcc.gnu.org/ml/gcc/2002-08/msg00822.html.

In Tru64 UNIX V5.1, Compaq introduced a new assembler that does not currently (2001-06-13) work with `mips-tfile`. As a workaround, we need to use the old assembler, invoked via the barely documented `-oldas` option. To bootstrap GCC, you either need to use the Compaq C Compiler:

       % CC=cc srcdir/configure [options] [target]

or you can use a copy of GCC 2.95.3 or higher built on Tru64 UNIX V4.0:

       % CC=gcc -Wa,-oldas srcdir/configure [options] [target]

As of GNU binutils 2.11.2, neither GNU `as` nor GNU `ld` are supported on Tru64 UNIX, so you must not configure GCC with `--with-gnu-as` or `--with-gnu-ld`.

The `--enable-threads` options isn't supported yet. A patch is in preparation for a future release.

GCC 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.

GCC 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, GCC 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.

### alphaev5-cray-unicosmk*

Cray T3E systems running Unicos/Mk.

This port is incomplete and has many known bugs. We hope to improve the support for this target soon. Currently, only the C front end is supported, and it is not possible to build parallel applications. Cray modules are not supported; in particular, Craylibs are assumed to be in `/opt/ctl/craylibs/craylibs`.

You absolutely must use GNU make on this platform. Also, you need to tell GCC where to find the assembler and the linker. The simplest way to do so is by providing `--with-as` and `--with-ld` to `configure`, e.g.

        configure --with-as=/opt/ctl/bin/cam --with-ld=/opt/ctl/bin/cld \
          --enable-languages=c

The comparison test during `make bootstrap` fails on Unicos/Mk because the assembler inserts timestamps into object files. You should be able to work around this by doing `make all` after getting this failure.

### arc-*-elf

Argonaut ARC processor. This configuration is intended for embedded systems.

### arm-*-aout

This configuration is obsoleted in GCC 3.3.

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-*-elf

This configuration is intended for embedded systems.

### arm*-*-linux-gnu

We require GNU binutils 2.10 or newer.

### avr

ATMEL AVR-family micro controllers. These are used in embedded applications. There are no standard Unix configurations. See "AVR Options" in the main manual for the list of supported MCU types.

Use `configure --target=avr --enable-languages="c"` to configure GCC.

Further installation notes and other useful information about AVR tools can also be obtained from:

- http://www.openavr.org
- http://home.overta.ru/users/denisc/
- http://www.amelek.gda.pl/avr/

We strongly recommend using binutils 2.13 or newer.

The following error:

      Error: register required

indicates that you should upgrade to a newer version of the binutils.

### c4x

Texas Instruments TMS320C3x and TMS320C4x Floating Point Digital Signal Processors. These are used in embedded applications. There are no standard Unix configurations. See "TMS320C3x/C4x Options" in the main manual for the list of supported MCU types.

GCC can be configured as a cross compiler for both the C3x and C4x architectures on the same system. Use `configure --target=c4x --enable-languages="c,c++"` to configure.

Further installation notes and other useful information about C4x tools can also be obtained from:

- http://www.elec.canterbury.ac.nz/c4x/

### CRIS

CRIS is the CPU architecture in Axis Communications ETRAX system-on-a-chip series. These are used in embedded applications.

See "CRIS Options" in the main manual for a list of CRIS-specific options.

There are a few different CRIS targets:

`cris-axis-aout`
  Old target. Includes a multilib for the `elinux` a.out-based target. No multilibs for newer architecture variants.
`cris-axis-elf`
  Mainly for monolithic embedded systems. Includes a multilib for the `v10` core used in `ETRAX 100 LX`.
`cris-axis-linux-gnu`
  A GNU/Linux port for the CRIS architecture, currently targeting `ETRAX 100 LX` by default.

For `cris-axis-aout` and `cris-axis-elf` you need binutils 2.11 or newer. For `cris-axis-linux-gnu` you need binutils 2.12 or newer.

Pre-packaged tools can be obtained from ftp://ftp.axis.com/pub/axis/tools/cris/compiler-kit/. More information about this platform is available at http://developer.axis.com/.

### DOS

Please have a look at our binaries page.

You cannot install GCC by itself on MSDOS; it will not compile under any MSDOS compiler except itself. You need to get the complete compilation package DJGPP, which includes binaries as well as sources, and includes all the necessary compilation tools and libraries.

### dsp16xx

A port to the AT&T DSP1610 family of processors.

### *-*-freebsd*

The version of binutils installed in `/usr/bin` is known to work unless otherwise specified in any per-architecture notes. However, binutils 2.12.1 or greater is known to improve overall testsuite results.

Support for FreeBSD 1 was discontinued in GCC 3.2.

For FreeBSD 2 or any mutant a.out versions of FreeBSD 3: All configuration support and files as shipped with GCC 2.95 are still in place. FreeBSD 2.2.7 has been known to bootstrap completely; however, it is unknown which version of binutils was used (it is assumed that it was the system copy in `/usr/bin`) and C++ EH failures were noted.

For FreeBSD using the ELF file format: DWARF 2 debugging is now the default for all CPU architectures. It had been the default on FreeBSD/alpha since its inception. You may use `-gstabs` instead of `-g`, if you really want the old debugging format. There are no known issues with mixing object files and libraries with different debugging formats. Otherwise, this release of GCC should now match more of the configuration used in the stock FreeBSD configuration of GCC. In particular, `--enable-threads` is now configured by default. However, as a general user, do not attempt to replace the system compiler with this release. Known to bootstrap and check with good results on FreeBSD 4.8-STABLE and 5-CURRENT. In the past, known to bootstrap and check with good results on FreeBSD 3.0, 3.4, 4.0, 4.2, 4.3, 4.4, 4.5-STABLE.

In principle, `--enable-threads` is now compatible with `--enable-libgcj` on FreeBSD. However, it has only been built and tested on `i386-*-freebsd[45]` and `alpha-*-freebsd[45]`. The static library may be incorrectly built (symbols are missing at link time). There is a rare timing-based startup hang (probably involves an assumption about the thread library). Multi-threaded boehm-gc (required for libjava) exposes severe threaded signal-handling bugs on FreeBSD before 4.5-RELEASE. Other CPU architectures supported by FreeBSD will require additional configuration tuning in, at the very least, both boehm-gc and libffi.

Shared `libgcc_s.so` is now built and installed by default.

### h8300-hms

Renesas H8/300 series of processors.

Please have a look at our binaries page.

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*-hp-hpux*

Support for HP-UX versions 7, 8, and 9 is obsoleted in GCC 3.3.

We highly recommend using gas/binutils 2.8 or newer on all hppa platforms; you may encounter a variety of problems when using the HP assembler.

Specifically, `-g` does not work on HP-UX (since that system uses a peculiar debugging format which GCC does not know about), unless you use GAS and GDB and configure GCC with the `--with-gnu-as` and `--with-as=...` options.

If you wish to use the pa-risc 2.0 architecture support with a 32-bit runtime, you must use either the HP assembler, gas/binutils 2.11 or newer, or a recent snapshot of gas.

There are two default scheduling models for instructions. These are PROCESSOR_7100LC and PROCESSOR_8000. They are selected from the pa-risc architecture specified for the target machine when configuring. PROCESSOR_8000 is the default. PROCESSOR_7100LC is selected when the target is a `hppa1*` machine.

The PROCESSOR_8000 model is not well suited to older processors. Thus, it is important to completely specify the machine architecture when configuring if you want a model other than PROCESSOR_8000. The macro TARGET_SCHED_DEFAULT can be defined in BOOT_CFLAGS if a different default scheduling model is desired.

More specific information to `hppa*-hp-hpux*` targets follows.

### hppa*-hp-hpux9

Support for this system is obsoleted in GCC 3.3.

The HP assembler has major problems on this platform. We've tried to work around the worst of the problems. However, those workarounds may be causing linker crashes in some circumstances; the workarounds also probably prevent shared libraries from working. Use the GNU assembler to avoid these problems.

The configuration scripts for GCC will also trigger a bug in the hpux9 shell. To avoid this problem set `CONFIG_SHELL` to `/bin/ksh` and `SHELL` to `/bin/ksh` in your environment.

### hppa*-hp-hpux10

For hpux10.20, we highly recommend you pick up the latest sed patch `PHCO_19798` from HP. HP has two sites which provide patches free of charge:

- US, Canada, Asia-Pacific, and Latin-America
- http://europe.itrc.hp.com/service/home/home.do Europe.

The HP assembler on these systems is much better than the hpux9 assembler, but still has some problems. Most notably the assembler inserts timestamps into each object file it creates, causing the 3-stage comparison test to fail during a `make bootstrap`. You should be able to continue by saying `make all` after getting the failure from `make bootstrap`.

### hppa*-hp-hpux11

GCC 3.0 and up support HP-UX 11. On 64-bit capable systems, there are two distinct ports. The `hppa2.0w-hp-hpux11*` port generates code for the 32-bit pa-risc runtime architecture. It uses the HP linker. The `hppa64-hp-hpux11*` port generates 64-bit code for the pa-risc 2.0 architecture. The script config.guess now selects the port type based on the type compiler detected during configuration. You must set your `PATH` or define `CC` so that configure finds an appropriate compiler for the initial bootstrap. Different prefixes must be used if both ports are to be installed on the same system.

It is best to explicitly configure the `hppa64-hp-hpux11*` target with the `--with-ld=...` option. We support both the HP and GNU linkers for this target. The two linkers require different link commands. Thus, it's not possible to switch linkers during a GCC build. This has been been reported to occur in a unified build of binutils and GCC.

GCC 2.95.x is not supported under HP-UX 11 and cannot be used to compile GCC 3.0 and up. Refer to binaries for information about obtaining precompiled GCC binaries for HP-UX.

You must use GNU binutils 2.11 or above with the 32-bit port. Thread support is not currently implemented, so `--enable-threads` does not work. See:

- http://gcc.gnu.org/ml/gcc-prs/2002-01/msg00551.html
- http://gcc.gnu.org/ml/gcc-bugs/2002-01/msg00663.html

GCC 3.3 and later support weak symbols on the 32-bit port using SOM secondary definition symbols. This feature is not enabled for earlier versions of HP-UX since there have been bugs in the linker support for secondary symbols. The HP linker patches `PHSS_26559` and `PHSS_24304` for HP-UX 11.00 and 11.11, respectively, correct the problem of linker core dumps creating C++ libraries. Earlier patches may work but they have not been tested.

GCC 3.3 nows uses the ELF DT_INIT_ARRAY and DT_FINI_ARRAY capability to run initializers and finalizers on the 64-bit port. The feature requires CVS binutils as of January 2, 2003, or a subsequent release to correct a problem arising from HP's non-standard use of the .init and .fini sections. The 32-bit port uses the linker `+init` and `+fini` options. As with the support for secondary symbols, there have been bugs in the order in which these options are executed by the HP linker. So, again a recent linker patch is recommended.

The HP assembler has many limitations and is not recommended for either the 32 or 64-bit ports. For example, it does not support weak symbols or alias definitions. As a result, explicit template instantiations are required when using C++. This will make it difficult if not impossible to build many C++ applications. You also can't generate debugging information when using the HP assembler with GCC.

There are a number of issues to consider in selecting which linker to use with the 64-bit port. The GNU 64-bit linker can only create dynamic binaries. The `-static` option causes linking with archive libraries but doesn't produce a truly static binary. Dynamic binaries still require final binding by the dynamic loader to resolve a set of dynamic-loader-defined symbols. The default behavior of the HP linker is the same as the GNU linker. However, it can generate true 64-bit static binaries using the `+compat` option.

The HP 64-bit linker doesn't support linkonce semantics. As a result, C++ programs have many more sections than they should.

The GNU 64-bit linker has some issues with shared library support and exceptions. As a result, we only support libgcc in archive format. For similar reasons, dwarf2 unwind and exception support are disabled. The GNU linker also has problems creating binaries with `-static`. It doesn't provide stubs for internal calls to global functions in shared libraries, so these calls can't be overloaded.

There are several possible approaches to building the distribution. Binutils can be built first using the HP tools. Then, the GCC distribution can be built. The second approach is to build GCC first using the HP tools, then build binutils, then rebuild GCC. There have been problems with various binary distributions, so it is best not to start from a binary distribution.

When starting with a HP compiler, it is preferable to use the ANSI compiler as the bundled compiler only supports traditional C. Bootstrapping with the bundled compiler is tested infrequently and problems often arise because of the subtle differences in semantics between traditional and ISO C.

This port still is undergoing significant development.

### i370-*-*

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

### *-*-linux-gnu

Versions of libstdc++-v3 starting with 3.2.1 require bugfixes present in glibc 2.2.5 and later. More information is available in the libstdc++-v3 documentation.

If you use glibc 2.2 (or 2.1.9x), GCC 2.95.2 won't install out-of-the-box. You'll get compile errors while building `libstdc++`. The patch glibc-2.2.patch, that is to be applied in the GCC source tree, fixes the compatibility problems.

Currently Glibc 2.2.3 (and older releases) and GCC 3.0 are out of sync since the latest exception handling changes for GCC. Compiling glibc with GCC 3.0 will give a binary incompatible glibc and therefore cause lots of problems and might make your system completely unusable. This will definitely need fixes in glibc but might also need fixes in GCC. We strongly advise to wait for glibc 2.2.4 and to read the release notes of glibc 2.2.4 whether patches for GCC 3.0 are needed. You can use glibc 2.2.3 with GCC 3.0, just do not try to recompile it.

### i?86-*-linux*aout

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.

### i?86-*-linux*

As of GCC 3.3, binutils 2.13.1 or later is required for this platform. See bug 10877 for more information.

If you receive Signal 11 errors when building on GNU/Linux, then it is possible you have a hardware problem. Further information on this can be found on www.bitwizard.nl.

### i?86-*-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.

### i?86-*-sco3.2v4

Use this configuration for SCO release 3.2 version 4.

### i?86-*-sco3.2v5*

Use this for the SCO OpenServer Release 5 family of operating systems.

Unlike earlier versions of GCC, the ability to generate COFF with this target is no longer provided.

Earlier versions of GCC emitted DWARF 1 when generating ELF to allow the system debugger to be used. That support was too burdensome to maintain. GCC now emits only DWARF 2 for this target. This means you may use either the UDK debugger or GDB to debug programs built by this version of GCC.

Use of the `-march=pentiumpro` flag can result in unrecognized opcodes when using the native assembler on OS versions before 5.0.6. (Support for P6 opcodes was added to the native ELF assembler in that version.) While it's rather rare to see these emitted by GCC yet, errors of the basic form:

      /usr/tmp/ccaNlqBc.s:22:unknown instruction: fcomip
      /usr/tmp/ccaNlqBc.s:50:unknown instruction: fucomip

are symptoms of this problem. You may work around this by not building affected files with that flag, by using the GNU assembler, or by using the assembler provided with the current version of the OS. Users of GNU assembler should see the note below for hazards on doing so.

The native SCO assembler that is provided with the OS at no charge is normally required. If, however, you must be able to use the GNU assembler (perhaps you're compiling code with asms that require GAS syntax) you may configure this package using the flags `--with-gnu-as`. You must use a recent version of GNU binutils; versions past 2.9.1 seem to work well.

In general, the `--with-gnu-as` option isn't as well tested as the native assembler.

Look in `gcc/config/i386/sco5.h` (search for "messy") for additional OpenServer-specific flags.

Systems based on OpenServer before 5.0.4 (`uname -X` will tell you what you're running) require TLS597 from ftp://stage.caldera.com/TLS/ for C++ constructors and destructors to work right.

The system linker in (at least) 5.0.4 and 5.0.5 will sometimes do the wrong thing for a construct that GCC will emit for PIC code. This can be seen as execution testsuite failures when using `-fPIC` on `921215-1.c`, `931002-1.c`, `nestfunc-1.c`, and `gcov-1.c`. For 5.0.5, an updated linker that will cure this problem is available. You must install both ftp://ftp.sco.com/pub/openserver5/rs505a and OSS499A.

The dynamic linker in OpenServer 5.0.5 (earlier versions may show the same problem) aborts on certain G77-compiled programs. It's particularly likely to be triggered by building Fortran code with the `-fPIC` flag. Although it's conceivable that the error could be triggered by other code, only G77-compiled code has been observed to cause this abort. If you are getting core dumps immediately upon execution of your G77 program--and especially if it's compiled with `-fPIC`--try applying `sco_osr5_g77.patch` to your `libf2c` and rebuilding GCC. Affected faults, when analyzed in a debugger, will show a stack backtrace with a fault occurring in `rtld()` and the program running as `/usr/lib/ld.so.1`. This problem has been reported to SCO engineering and will hopefully be addressed in later releases.

### i?86-*-udk

This target emulates the SCO Universal Development Kit and requires that package be installed. (If it is installed, you will have a `/udk/usr/ccs/bin/cc` file present.) It's very much like the `i?86-*-unixware7*` target but is meant to be used when hosting on a system where UDK isn't the default compiler such as OpenServer 5 or Unixware 2. This target will generate binaries that will run on OpenServer, Unixware 2, or Unixware 7, with the same warnings and caveats as the SCO UDK.

This target is a little tricky to build because we have to distinguish it from the native tools (so it gets headers, startups, and libraries from the right place) while making the tools not think we're actually building a cross compiler. The easiest way to do this is with a configure command like this:

        CC=/udk/usr/ccs/bin/cc /your/path/to/gcc/configure \
          --host=i686-pc-udk --target=i686-pc-udk --program-prefix=udk-

You should substitute `i686` in the above command with the appropriate processor for your host.

After the usual `make bootstrap` and `make install`, you can then access the UDK-targeted GCC tools by adding `udk-` before the commonly known name. For example, to invoke the C compiler, you would use `udk-gcc`. They will coexist peacefully with any native-target GCC tools you may have installed.

### ia64-*-linux

IA-64 processor (also known as IPF, or Itanium Processor Family) running GNU/Linux.

The toolchain is not completely finished, so requirements will continue to change. GCC 3.0.1 and later require glibc 2.2.4. GCC 3.0.2 requires binutils from 2001-09-05 or later. GCC 3.0.1 requires binutils 2.11.1 or later.

None of the following versions of GCC has an ABI that is compatible with any of the other versions in this list, with the exception that Red Hat 2.96 and Trillian 000171 are compatible with each other: 3.0.2, 3.0.1, 3.0, Red Hat 2.96, and Trillian 000717. This primarily affects C++ programs and programs that create shared libraries. Because of these ABI incompatibilities, GCC 3.0.2 is not recommended for user programs on GNU/Linux systems built using earlier compiler releases. GCC 3.0.2 is recommended for compiling linux, the kernel. GCC 3.0.2 is believed to be fully ABI compliant, and hence no more major ABI changes are expected.

### ia64-*-hpux*

Building GCC on this target requires the GNU Assembler. The bundled HP assembler will not work. To prevent GCC from using the wrong assembler, the option `--with-gnu-as` may be necessary.

The GCC libunwind library has not been ported to HPUX. This means that for GCC versions 3.2.3 and earlier, `--enable-libunwind-exceptions` is required to build GCC. For GCC 3.3 and later, this is the default.

### *-lynx-lynxos

Support for SPARC LynxOS is obsoleted in GCC 3.3.

LynxOS 2.2 and earlier comes with GCC 1.x already installed as `/bin/gcc`. You should compile with this instead of `/bin/cc`. You can tell GCC 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 GCC will use the installed tools, which produce `a.out` format executables.

### *-ibm-aix*

Support for AIX versions 1, 2, and 3 is obsoleted in GCC 3.3.

AIX Make frequently has problems with GCC makefiles. GNU Make 3.76 or newer is recommended to build on this platform.

Errors involving `alloca` when building GCC generally are due to an incorrect definition of `CC` in the Makefile or mixing files compiled with the native C compiler and GCC. During the stage1 phase of the build, the native AIX compiler must be invoked as `cc` (not `xlc`). Once `configure` has been informed of `xlc`, one needs to use `make distclean` to remove the configure cache files and ensure that `CC` environment variable does not provide a definition that will confuse `configure`. If this error occurs during stage2 or later, then the problem most likely is the version of Make (see above).

The native `as` and `ld` are recommended for bootstrapping on AIX 4 and required for bootstrapping on AIX 5L. The GNU Assembler reports that it supports WEAK symbols on AIX 4, which causes GCC to try to utilize weak symbol functionality although it is not supported. The GNU Assembler and Linker do not support AIX 5L sufficiently to bootstrap GCC. The native AIX tools do interoperate with GCC.

Building `libstdc++.a` requires a fix for an AIX Assembler bug APAR IY26685 (AIX 4.3) or APAR IY25528 (AIX 5.1).

`libstdc++` in GCC 3.2 increments the major version number of the shared object and GCC installation places the `libstdc++.a` shared library in a common location which will overwrite the GCC 3.1 version of the shared library. Applications either need to be re-linked against the new shared library or the GCC 3.1 version of the `libstdc++` shared object needs to be available to the AIX runtime loader. The GCC 3.1 `libstdc++.so.4` shared object can be installed for runtime dynamic loading using the following steps to set the `F_LOADONLY` flag in the shared object for each multilib `libstdc++.a` installed:

Extract the shared object from each the GCC 3.1 `libstdc++.a` archive:

       % ar -x libstdc++.a libstdc++.so.4

Enable the `F_LOADONLY` flag so that the shared object will be available for runtime dynamic loading, but not linking:

       % strip -e libstdc++.so.4

Archive the runtime-only shared object in the GCC 3.2 `libstdc++.a` archive:

       % ar -q libstdc++.a libstdc++.so.4

Linking executables and shared libraries may produce warnings of duplicate symbols. The assembly files generated by GCC for AIX always have 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.

AIX 4.3 utilizes a "large format" archive to support both 32-bit and 64-bit object modules. The routines provided in AIX 4.3.0 and AIX 4.3.1 to parse archive libraries did not handle the new format correctly. These routines are used by GCC and result in error messages during linking such as "not a COFF file". The version of the routines shipped with AIX 4.3.1 should work for a 32-bit environment. The `-g` option of the archive command may be used to create archives of 32-bit objects using the original "small format". A correct version of the routines is shipped with AIX 4.3.2 and above.

Some versions of the AIX binder (linker) can fail with a relocation overflow severe error when the `-bbigtoc` option is used to link GCC-produced object files into an executable that overflows the TOC. A fix for APAR IX75823 (OVERFLOW DURING LINK WHEN USING GCC AND -BBIGTOC) is available from IBM Customer Support and from its techsupport.services.ibm.com website as PTF U455193.

The AIX 4.3.2.1 linker (bos.rte.bind_cmds Level 4.3.2.1) will dump core with a segmentation fault when invoked by any version of GCC. A fix for APAR IX87327 is available from IBM Customer Support and from its techsupport.services.ibm.com website as PTF U461879. This fix is incorporated in AIX 4.3.3 and above.

The initial assembler shipped with AIX 4.3.0 generates incorrect object files. A fix for APAR IX74254 (64BIT DISASSEMBLED OUTPUT FROM COMPILER FAILS TO ASSEMBLE/BIND) is available from IBM Customer Support and from its techsupport.services.ibm.com website as PTF U453956. This fix is incorporated in AIX 4.3.1 and above.

AIX provides National Language Support (NLS). Compilers and assemblers use NLS to support locale-specific representations of various data formats including floating-point numbers (e.g., `.` vs `,` for separating decimal fractions). There have been problems reported where GCC does not produce the same floating-point formats that the assembler expects. If one encounters this problem, set the `LANG` environment variable to `C` or `En_US`.

By default, GCC for AIX 4.1 and above produces code that can be used on both Power or PowerPC processors.

A default can be specified with the `-mcpu=cpu_type` switch and using the configure option `--with-cpu-cpu_type`.

### ip2k-*-elf

Ubicom IP2022 micro controller. This configuration is intended for embedded systems. There are no standard Unix configurations.

Use `configure --target=ip2k-elf --enable-languages=c` to configure GCC.

### m32r-*-elf

Renesas M32R processor. This configuration is intended for embedded systems.

### m68000-hp-bsd

Support for this system is obsoleted in GCC 3.3.

HP 9000 series 200 running BSD. Note that the C compiler that comes with this system cannot compile GCC; contact law@cygnus.com to get binaries of GCC for bootstrapping.

### m6811-elf

Motorola 68HC11 family micro controllers. These are used in embedded applications. There are no standard Unix configurations.

### m6812-elf

Motorola 68HC12 family micro controllers. These are used in embedded applications. There are no standard Unix configurations.

### m68k-att-sysv

Support for this system is obsoleted in GCC 3.3.

AT&T 3b1, a.k.a. 7300 PC. This version of GCC cannot be compiled with the system C compiler, which is too buggy. You will need to get a previous version of GCC and use it to bootstrap. Binaries are available from the OSU-CIS archive, at ftp://ftp.uu.net/systems/att7300/.

### m68k-crds-unos

Support for this system is obsoleted in GCC 3.3.

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 GCC, 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 GCC to function, either change all references to `-lc` in `gcc.c` to `-lunos` or link `/lib/libc.a` to `/lib/libunos.a`.

When compiling GCC 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 GCC. This bug manifests itself during the first stage of compilation, while building `libgcc2.a`:

    _floatdisf
    cc1: warning: `-g' option not supported on this version of GCC
    cc1: warning: `-g1' option not supported on this version of GCC
    ./xgcc: Internal compiler error: program as got fatal signal 11

A patched version of the assembler is available as the file ftp://altdorf.ai.mit.edu/archive/cph/hpux-8.0-assembler. If you have HP software support, the patch can also be obtained directly from HP, as described in the following note:

> This is the patched assembler, to patch SR#1653-010439, where the assembler aborts on floating point constants.

> The bug is not really in the assembler, but in the shared library version of the function "cvtnum(3c)". The bug on "cvtnum(3c)" is SR#4701-078451. Anyway, the attached assembler uses the archive library version of "cvtnum(3c)" and thus does not exhibit the bug.

This patch is also known as PHCO_4484.

In addition, if you wish to use gas, 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.

On HP-UX version 8.05, but not on 8.07 or more recent versions, the `fixproto` shell script triggers a bug in the system shell. If you encounter this problem, upgrade your operating system or use BASH (the GNU shell) to run `fixproto`. This bug will cause the fixproto program to report an error of the form:

    ./fixproto: sh internal 1K buffer overflow

To fix this, you can also change the first line of the fixproto script to look like:

    #!/bin/ksh

### m68k-ncr-*

Support for this system is obsoleted in GCC 3.3.

On the Tower models 4n0 and 6n0, by default a process is not allowed to have more than one megabyte of memory. GCC cannot compile itself (or many other programs) with `-O` in that much memory.

To solve this problem, reconfigure the kernel adding the following line to the configuration file:

    MAXUMEM = 4096

### m68k-sun

Support for this system is obsoleted in GCC 3.3.

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.

### m68k-sun-sunos4.1.1

Support for this system is obsoleted in GCC 3.3.

It is reported that you may need the GNU assembler on this platform.

### mips-*-*

If on a MIPS system you get an error message saying "does not have gp sections for all it's [sic] sectons [sic]", don't worry about it. This happens whenever you use GAS with the MIPS linker, but there is not really anything wrong, and it is okay to use the output file. You can stop such warnings by installing the GNU linker.

It would be nice to extend GAS to produce the gp tables, but they are optional, and there should not be a warning about their absence.

The libstdc++ atomic locking routines for MIPS targets requires MIPS II and later. A patch went in just after the GCC 3.3 release to make `mips*-*-*` use the generic implementation instead. You can also configure for `mipsel-elf` as a workaround. The `mips*-*-linux*` target continues to use the MIPS II routines. More work on this is expected in future releases.

### mips-sgi-irix5

This configuration has considerable problems, which will be fixed in a future release.

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. It is also available for download from http://www.sgi.com/developers/devtools/apis/ido.html.

`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.

If you use the MIPS C compiler to bootstrap, it may be necessary to increase its table size for switch statements with the `-Wf,-XNg1500` option. If you use the `-O2` optimization option, you also need to use `-Olimit 3000`.

To enable debugging under IRIX 5, you must use GNU `as` 2.11.2 or later, and use the `--with-gnu-as` configure option when configuring GCC. GNU `as` is distributed as part of the binutils package. When using release 2.11.2, you need to apply a patch http://sources.redhat.com/ml/binutils/2001-07/msg00352.html which will be included in the next release of binutils.

When building GCC, the build process loops rebuilding `cc1` over and over again. This happens on `mips-sgi-irix5.2`, and possibly other platforms. It has been reported that this is a known bug in the `make` shipped with IRIX 5.2. We recommend you use GNU `make` instead of the vendor supplied `make` program; however, you may have success with `smake` on IRIX 5.2 if you do not have GNU `make` available.

### mips-sgi-irix6

If you are using IRIX `cc` as your bootstrap compiler, you must ensure that the N32 ABI is in use. To test this, compile a simple C file with `cc` and then run `file` on the resulting object file. The output should look like:

    test.o: ELF N32 MSB ...

If you see:

    test.o: ELF 32-bit MSB ...

or

    test.o: ELF 64-bit MSB ...

then your version of `cc` uses the O32 or N64 ABI by default. You should set the environment variable `CC` to `cc -n32` before configuring GCC.

If you want the resulting `gcc` to run on old 32-bit systems with the MIPS R4400 CPU, you need to ensure that only code for the mips3 instruction set architecture (ISA) is generated. While GCC 3.x does this correctly, both GCC 2.95 and SGI's MIPSpro `cc` may change the ISA depending on the machine where GCC is built. Using one of them as the bootstrap compiler may result in mips4 code, which won't run at all on mips3-only systems. For the test program above, you should see:

    test.o: ELF N32 MSB mips-3 ...

If you get:

    test.o: ELF N32 MSB mips-4 ...

instead, you should set the environment variable `CC` to `cc -n32 -mips3` or `gcc -mips3` respectively before configuring GCC.

GCC on IRIX 6 is usually built to support both the N32 and N64 ABIs. If you build GCC on a system that doesn't have the N64 libraries installed, you need to configure with `--disable-multilib` so GCC doesn't try to use them. Look for `/usr/lib64/libc.so.1` to see if you have the 64-bit libraries installed.

You must not use GNU `as` (which isn't built anyway as of binutils 2.11.2) on IRIX 6 platforms; doing so will only cause problems.

GCC does not currently support generating O32 ABI binaries in the `mips-sgi-irix6` configurations. It is possible to create a GCC with O32 ABI only support by configuring it for the `mips-sgi-irix5` target and using a patched GNU `as` 2.11.2 as documented in the `mips-sgi-irix5` section above. Using the native assembler requires patches to GCC which will be included in a future release. It is expected that O32 ABI support will be available again in a future release.

The `--enable-threads` option doesn't currently work, a patch is in preparation for a future release. The `--enable-libgcj` option is disabled by default: IRIX 6 uses a very low default limit (20480) for the command line length. Although libtool contains a workaround for this problem, at least the N64 `libgcj` is known not to build despite this, running into an internal error of the native `ld`. A sure fix is to increase this limit (`ncargs`) to its maximum of 262144 bytes. If you have root access, you can use the `systune` command to do this.

GCC does not correctly pass/return structures which are smaller than 16 bytes and which are not 8 bytes. The problem is very involved and difficult to fix. It affects a number of other targets also, but IRIX 6 is affected the most, because it is a 64-bit target, and 4 byte structures are common. The exact problem is that structures are being padded at the wrong end, e.g. a 4 byte structure is loaded into the lower 4 bytes of the register when it should be loaded into the upper 4 bytes of the register.

GCC is consistent with itself, but not consistent with the SGI C compiler (and the SGI supplied runtime libraries), so the only failures that can happen are when there are library functions that take/return such structures. There are very few such library functions. Currently this is known to affect `inet_ntoa`, `inet_lnaof`, `inet_netof`, `inet_makeaddr`, and `semctl`. Until the bug is fixed, GCC contains workarounds for the known affected functions.

See http://freeware.sgi.com/ for more information about using GCC on IRIX platforms.

### powerpc-*-*

You can specify a default version for the `-mcpu=cpu_type` switch by using the configure option `--with-cpu-cpu_type`.

### powerpc-*-darwin*

PowerPC running Darwin (Mac OS X kernel).

Pre-installed versions of Mac OS X may not include any developer tools, meaning that you will not be able to build GCC from source. Tool binaries are available at http://developer.apple.com/tools/compilers.html (free registration required).

The default stack limit of 512K is too small, which may cause compiles to fail with 'Bus error'. Set the stack larger, for instance by doing `limit stack 800`. It's a good idea to use the GNU preprocessor instead of Apple's `cpp-precomp` during the first stage of bootstrapping; this is automatic when doing `make bootstrap`, but to do it from the toplevel objdir you will need to say `make CC='cc -no-cpp-precomp' bootstrap`.

The version of GCC shipped by Apple typically includes a number of extensions not available in a standard GCC release. These extensions are generally specific to Mac programming.

### powerpc-*-elf, powerpc-*-sysv4

PowerPC system in big endian mode, running System V.4.

### powerpc-*-linux-gnu*

You will need binutils 2.13.90.0.10 or newer for a working GCC.

### powerpc-*-netbsd*

PowerPC system in big endian mode running NetBSD. To build the documentation you will need Texinfo version 4.2 (NetBSD 1.5.1 included Texinfo version 3.12).

### powerpc-*-eabiaix

Embedded PowerPC system in big endian mode with `-mcall-aix` selected as the default.

### powerpc-*-eabisim

Embedded PowerPC system in big endian mode for use in running under the PSIM simulator.

### powerpc-*-eabi

Embedded PowerPC system in big endian mode.

### powerpcle-*-elf, powerpcle-*-sysv4

PowerPC system in little endian mode, running System V.4.

### powerpcle-*-eabisim

Embedded PowerPC system in little endian mode for use in running under the PSIM simulator.

### powerpcle-*-eabi

Embedded PowerPC system in little endian mode.

### s390-*-linux*

S/390 system running Linux for S/390.

### s390x-*-linux*

zSeries system (64-bit) running Linux for zSeries.

### *-*-solaris2*

Sun does not ship a C compiler with Solaris 2. To bootstrap and install GCC you first have to install a pre-built compiler, see our binaries page for details.

The Solaris 2 `/bin/sh` will often fail to configure `libstdc++-v3`, `boehm-gc` or `libjava`. We therefore recommend to use the following sequence of commands to bootstrap and install GCC:

       % CONFIG_SHELL=/bin/ksh
       % export CONFIG_SHELL
       % srcdir/configure [options] [target]
       % gmake bootstrap
       % gmake install

As explained in the build instructions, we recommend to use GNU make, which we call `gmake` here to distinguish it from Sun make.

Solaris 2 comes with a number of optional OS packages. Some of these are needed to use GCC fully, namely `SUNWarc`, `SUNWbtool`, `SUNWesu`, `SUNWhea`, `SUNWlibm`, `SUNWsprot`, and `SUNWtoo`. If you did not install all optional packages when installing Solaris 2, you will need to verify that the packages that GCC needs are installed.

To check whether an optional package is installed, use the `pkginfo` command. To add an optional package, use the `pkgadd` command. For further details, see the Solaris 2 documentation.

Trying to use the linker and other tools in `/usr/ucb` to install GCC has been observed to cause trouble. For example, the linker may hang indefinitely. The fix is to remove `/usr/ucb` from your `PATH`.

The build process works more smoothly with the legacy Sun tools so, if you have `/usr/xpg4/bin` in your `PATH`, we recommend that you place `/usr/bin` before `/usr/xpg4/bin` for the duration of the build.

All releases of GNU binutils prior to 2.11.2 have known bugs on this platform. We recommend the use of GNU binutils 2.11.2 or the vendor tools (Sun `as`, Sun `ld`).

Sun bug 4296832 turns up when compiling X11 headers with GCC 2.95 or newer: `g++` will complain that types are missing. These headers assume that omitting the type means `int`; this assumption worked for C89 but is wrong for C++, and is now wrong for C99 also.

`g++` accepts such (invalid) constructs with the option `-fpermissive`; it will assume that any missing type is `int` (as defined by C89).

There are patches for Solaris 2.6 (105633-56 or newer for SPARC, 106248-42 or newer for Intel), Solaris 7 (108376-21 or newer for SPARC, 108377-20 for Intel), and Solaris 8 (108652-24 or newer for SPARC, 108653-22 for Intel) that fix this bug.

### sparc-sun-solaris2*

When GCC is configured to use binutils 2.11.2 or later the binaries produced are smaller than the ones produced using Sun's native tools; this difference is quite significant for binaries containing debugging information.

Sun `as` 4.x is broken in that it cannot cope with long symbol names. A typical error message might look similar to the following:

    /usr/ccs/bin/as: "/var/tmp/ccMsw135.s", line 11041: error:
      can't compute value of an expression involving an external symbol.

This is Sun bug 4237974. This is fixed with patch 108908-02 for Solaris 2.6 and has been fixed in later (5.x) versions of the assembler, starting with Solaris 7.

Starting with Solaris 7, the operating system is capable of executing 64-bit SPARC V9 binaries. GCC 3.1 and later properly supports this; the `-m64` option enables 64-bit code generation. However, if all you want is code tuned for the UltraSPARC CPU, you should try the `-mtune=ultrasparc` option instead, which produces code that, unlike full 64-bit code, can still run on non-UltraSPARC machines.

When configuring on a Solaris 7 or later system that is running a kernel that supports only 32-bit binaries, one must configure with `--disable-multilib`, since we will not be able to build the 64-bit target libraries.

### sparc-sun-solaris2.7

Sun patch 107058-01 (1999-01-13) for Solaris 7/SPARC triggers a bug in the dynamic linker. This problem (Sun bug 4210064) affects GCC 2.8 and later, including all EGCS releases. Sun formerly recommended 107058-01 for all Solaris 7 users, but around 1999-09-01 it started to recommend it only for people who use Sun's compilers.

Here are some workarounds to this problem:

- Do not install Sun patch 107058-01 until after Sun releases a complete patch for bug 4210064. This is the simplest course to take, unless you must also use Sun's C compiler. Unfortunately 107058-01 is preinstalled on some new Solaris 7-based hosts, so you may have to back it out.
- Copy the original, unpatched Solaris 7 `/usr/ccs/bin/as` into `/usr/local/lib/gcc-lib/sparc-sun-solaris2.7/3.1/as`, adjusting the latter name to fit your local conventions and software version numbers.
- Install Sun patch 106950-03 (1999-05-25) or later. Nobody with both 107058-01 and 106950-03 installed has reported the bug with GCC and Sun's dynamic linker. This last course of action is riskiest, for two reasons. First, you must install 106950 on all hosts that run code generated by GCC; it doesn't suffice to install it only on the hosts that run GCC itself. Second, Sun says that 106950-03 is only a partial fix for bug 4210064, but Sun doesn't know whether the partial fix is adequate for GCC. Revision -08 or later should fix the bug. The current (as of 2001-09-24) revision is -14, and is included in the Solaris 7 Recommended Patch Cluster.

GCC 3.3 triggers a bug in version 5.0 Alpha 03/27/98 of the Sun assembler, which causes a bootstrap failure when linking the 64-bit shared version of libgcc. A typical error message is:

    ld: fatal: relocation error: R_SPARC_32: file libgcc/sparcv9/_muldi3.o:
      symbol <unknown>:  offset 0xffffffff7ec133e7 is non-aligned.

This bug has been fixed in the final 5.0 version of the assembler.

### sparc-sun-sunos4*

Support for this system is obsoleted in GCC 3.3.

A bug in the SunOS 4 linker will cause it to crash when linking `-fPIC` compiled objects (and will therefore not allow you to build shared libraries).

To fix this problem you can either use the most recent version of binutils or get the latest SunOS 4 linker patch (patch ID 100170-10) from Sun's patch site.

Sometimes on a Sun 4 you may observe a crash in the program `genflags` or `genoutput` while building GCC. This is said to be due to a bug in `sh`. You can probably get around it by running `genflags` or `genoutput` manually and then retrying the `make`.

### sparc-unknown-linux-gnulibc1

Support for this system is obsoleted in GCC 3.3.

It has been reported that you might need binutils 2.8.1.0.23 for this platform, too.

### sparc-*-linux*

GCC versions 3.0 and higher require binutils 2.11.2 and glibc 2.2.4 or newer on this platform. All earlier binutils and glibc releases mishandled unaligned relocations on `sparc-*-*` targets.

### sparc64-*-solaris2*

The following compiler flags must be specified in the configure step in order to bootstrap this target with the Sun compiler:

       % CC="cc -xildoff -xarch=v9" srcdir/configure [options] [target]

`-xildoff` turns off the incremental linker, and `-xarch=v9` specifies the SPARC-V9 architecture to the Sun linker and assembler.

### sparcv9-*-solaris2*

This is a synonym for sparc64-*-solaris2*.

### *-*-sysv*

On System V release 3, you may get this error message while linking:

    ld fatal: failed to write symbol name something
     in strings table for file whatever

This probably indicates that the disk is full or your ulimit won't allow the file to be as large as it needs to be.

This problem can also result because the kernel parameter `MAXUMEM` is too small. If so, you must regenerate the kernel and make the value much larger. The default value is reported to be 1024; a value of 32768 is said to work. Smaller values may also work.

On System V, if you get an error like this,

    /usr/local/lib/bison.simple: In function `yyparse':
    /usr/local/lib/bison.simple:625: virtual memory exhausted

that too indicates a problem with disk space, ulimit, or `MAXUMEM`.

On a System V release 4 system, make sure `/usr/bin` precedes `/usr/ucb` in `PATH`. The `cc` command in `/usr/ucb` uses libraries which have bugs.

### vax-dec-ultrix

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

### xtensa-*-elf

This target is intended for embedded Xtensa systems using the `newlib` C library. It uses ELF but does not support shared objects. Designed-defined instructions specified via the Tensilica Instruction Extension (TIE) language are only supported through inline assembly.

The Xtensa configuration information must be specified prior to building GCC. The `gcc/config/xtensa/xtensa-config.h` header file contains the configuration information. If you created your own Xtensa configuration with the Xtensa Processor Generator, the downloaded files include a customized copy of this header file, which you can use to replace the default header file.

### xtensa-*-linux*

This target is for Xtensa systems running GNU/Linux. It supports ELF shared objects and the GNU C library (glibc). It also generates position-independent code (PIC) regardless of whether the `-fpic` or `-fPIC` options are used. In other respects, this target is the same as the `xtensa-*-elf` target.

### Microsoft Windows (32-bit)

A port of GCC 2.95.2 and 3.x is included with the Cygwin environment.

Current (as of early 2001) snapshots of GCC will build under Cygwin without modification.

GCC does not currently build with Microsoft's C++ compiler and there are no plans to make it do so.

### OS/2

GCC does not currently support OS/2. However, Andrew Zabolotny has been working on a generic OS/2 port with pgcc. The current code can be found at http://www.goof.com/pcg/os2/.

An older copy of GCC 2.8.1 is included with the EMX tools available at ftp://ftp.leo.org/pub/comp/os/os2/leo/devtools/emx+gcc/.

### Older systems

GCC contains support files for many older (1980s and early 1990s) Unix variants. For the most part, support for these systems has not been deliberately removed, but it has not been maintained for several years and may suffer from bitrot.

Starting with GCC 3.1, each release has a list of "obsoleted" systems. Support for these systems is still present in that release, but `configure` will fail unless the `--enable-obsolete` option is given. Unless a maintainer steps forward, support for these systems will be removed from the next release of GCC.

Support for old systems as hosts for GCC can cause problems if the workarounds for compiler, library and operating system bugs affect the cleanliness or maintainability of the rest of GCC. In some cases, to bring GCC up on such a system, if still possible with current GCC, may require first installing an old version of GCC which did work on that system, and using it to compile a more recent GCC, to avoid bugs in the vendor compiler. Old releases of GCC 1 and GCC 2 are available in the `old-releases` directory on the GCC mirror sites. Header bugs may generally be avoided using `fixincludes`, but bugs or deficiencies in libraries and the operating system may still cause problems.

Support for older systems as targets for cross-compilation is less problematic than support for them as hosts for GCC; if an enthusiast wishes to make such a target work again (including resurrecting any of the targets that never worked with GCC 2, starting from the last CVS version before they were removed), patches following the usual requirements would be likely to be accepted, since they should not affect the support for more modern targets.

For some systems, old versions of GNU binutils may also be useful, and are available from `pub/binutils/old-releases` on sources.redhat.com mirror sites.

Some of the information on specific systems above relates to such older systems, but much of the information about GCC on such systems (which may no longer be applicable to current GCC) is to be found in the GCC texinfo manual.

### all ELF targets (SVR4, Solaris 2, etc.)

C++ support is significantly better on ELF targets if you use the GNU linker; duplicate copies of inlines, vtables and template instantiations will be discarded automatically.

Return to the GCC Installation page