Installing the GNU C Library **************************** Installation of the GNU C library is relatively simple, but usually requires several GNU tools to be installed already. Before you do anything else, you should read the file `FAQ' found at the top level of the source tree. This file answers common questions and describes problems you may experience with compilation and installation. It is updated more frequently than this manual. To configure the GNU C library for your system, run the shell script `configure' with `sh'. You might use an argument which is the conventional GNU name for your system configuration--for example, `i486-pc-linux-gnu', for Linux running on i486. *Note Installation: (gcc.info)Installation, for a full description of standard GNU configuration names. If you omit the configuration name, `configure' will try to guess one for you by inspecting the system it is running on. It may or may not be able to come up with a guess, and the guess might be wrong. `configure' will tell you the canonical name of the chosen configuration before proceeding. Here are some options that you should specify (if appropriate) when you run `configure': `--with-binutils=DIRECTORY' Use the binutils (assembler and linker) in `DIRECTORY', not the ones the C compiler would default to. You could use this option if the default binutils on your system cannot deal with all the constructs in the GNU C library. (`configure' will detect the problem and suppress these constructs, so the library will still be usable, but functionality may be lost--for example, you can not build a shared libc with old binutils.) `--without-fp' `--nfp' Use this option if your computer lacks hardware floating-point support and your operating system does not emulate an FPU. `--prefix=DIRECTORY' Install machine-independent data files in subdirectories of `DIRECTORY'. (You can also set this in `configparms'; see below.) The default is to install in `/usr/local'. `--exec-prefix=DIRECTORY' Install the library and other machine-dependent files in subdirectories of `DIRECTORY'. (You can also set this in `configparms'; see below.) The default is to use /bin and /sbin. `--enable-shared' `--disable-shared' Enable or disable building of an ELF shared library on systems that support it. The default is to build the shared library on systems using ELF when the GNU `binutils' are available. `--enable-profile' `--disable-profile' Enable or disable building of the profiled C library, `-lc_p'. The default is to build the profiled library. You may wish to disable it if you don't plan to do profiling, because it doubles the build time of compiling just the unprofiled static library. `--enable-omitfp' Enable building a highly-optimized but possibly undebuggable C library. This causes the normal static and shared (if enabled) C libraries to be compiled with maximal optimization, including the `-fomit-frame-pointer' switch that makes debugging impossible on many machines, and without debugging information (which makes the binaries substantially smaller). An additional static library is compiled with no optimization and full debugging information, and installed as `-lc_g'. `--enable-add-ons[=LIST]' Certain components of the C library are distributed separately from the rest of the sources. In particular, the `crypt' function and its friends are separated due to US export control regulations, and the threading support code for Linux is maintained separately. You can get these "add-on" packages from the same place you got the libc sources. To use them, unpack them into your source tree, and give `configure' the `--enable-add-ons' option. If you do not wish to use some add-on package that you have present in your source tree, give this option a list of the add-ons that you *do* want used, like this: `--enable-add-ons=crypt,linuxthreads' `--with-headers=DIRECTORY' Search only DIRECTORY and the C compiler's private directory for header files not found in the libc sources. `/usr/include' will not be searched if this option is given. On Linux, DIRECTORY should be the kernel's private include directory (usually `/usr/src/linux/include'). This option is primarily of use on a system where the headers in `/usr/include' come from an older version of glibc. Conflicts can occasionally happen in this case. Note that Linux libc5 qualifies as an older version of glibc. You can also use this option if you want to compile glibc with a newer set of kernel headers than the ones found in `/usr/include'. You should not build the library in the same directory as the sources, because there are bugs in `make clean'. Make a directory for the build, and run `configure' from that directory, like this: mkdir linux cd linux ../configure `configure' looks for the sources in whatever directory you specified for finding `configure' itself. It does not matter where in the file system the source and build directories are--as long as you specify the source directory when you run `configure', you will get the proper results. This feature lets you keep sources and binaries in different directories, and that makes it easy to build the library for several different machines from the same set of sources. Simply create a build directory for each target machine, and run `configure' in that directory specifying the target machine's configuration name. The library has a number of special-purpose configuration parameters. These are defined in the file `configparms'; see the comments in that file for the details. To change them, copy `configparms' into your build directory and modify it as appropriate for your system. `configure' will not notice your modifications if you change the file in the source directory. It is easy to configure the GNU C library for cross-compilation by setting a few variables in `configparms'. Set `CC' to the cross-compiler for the target you configured the library for; it is important to use this same `CC' value when running `configure', like this: `CC=TARGET-gcc configure TARGET'. Set `BUILD_CC' to the compiler to use for for programs run on the build system as part of compiling the library. You may need to set `AR' and `RANLIB' to cross-compiling versions of `ar' and `ranlib' if the native tools are not configured to work with object files for the target you configured for. Some of the machine-dependent code for some machines uses extensions in the GNU C compiler, so you may need to compile the library with GCC. (In fact, all of the existing complete ports require GCC.) To build the library and related programs, type `make'. This will produce a lot of output, some of which may look like errors from `make' (but isn't). Look for error messages from `make' containing `***'. Those indicate that something is really wrong. The compilation process takes several hours even on fast hardware; expect at least two hours for the default configuration on i586 for Linux. For Hurd times are much longer. All current releases of GCC have a problem which causes them to take several minutes to compile certain files in the iconvdata directory. Do not panic if the compiler appears to hang. To build and run some test programs which exercise some of the library facilities, type `make check'. This will produce several files with names like `PROGRAM.out'. To format the `GNU C Library Reference Manual' for printing, type `make dvi'. You need a working TeX installation to do this. To install the library and its header files, and the Info files of the manual, type `make install'. This will build things if necessary, before installing them. If you want to install the files in a different place than the one specified at configuration time you can specify a value for the Makefile variable `install_root' on the command line. This is useful to create chroot'ed environment or to prepare binary releases. For now (in this alpha version, and at least on RedHat Linux), if you are trying to install this as your default libraries, a different installation method is recommended. Move `/usr/include' out of the way, create a new `/usr/include' directory (don't forget the symlinks `/usr/include/asm' and `/usr/include/linux', that should point to `/usr/src/linux/include/asm' and `/usr/src/linux/include/linux' -or wherever you keep your kernel sources-respectively), build normally and install into somewhere else via `install_root'. Then move your `/usr/include' back, and copy the newly created stuff by hand over the old. Remember to copy programs and shared libraries into `FILENAME.new' and then move `FILENAME.new' to `FILENAME', as the files might be in use. You will have to `ranlib' your copies of the static libraries `/usr/lib/libNAME.a'. You will see that `libbsd-compat.a', `libieee.a', and `libmcheck.a' are just object files, not archives. This is normal. Copy the new header files over the old ones by something like `cd /usr; (cd INSTALL_ROOT; tar cf - include) | tar xf -'. Recommended Tools to Install the GNU C Library ============================================== We recommend installing the following GNU tools before attempting to build the GNU C library: * GNU `make' 3.75 You need the latest version of GNU `make'. Modifying the GNU C Library to work with other `make' programs would be so hard that we recommend you port GNU `make' instead. *Really.* We recommend version GNU `make' version 3.75. Versions 3.76 and 3.76.1 are known to have bugs which only show up in big projects like GNU `libc'. * GCC 2.8.1/EGCS 1.0.2 On most platforms, the GNU C library can only be compiled with the GNU C compiler family. We recommend GCC version 2.8.1 and EGCS version 1.0.2 or later versions of these two; earlier versions may have problems. * GNU `binutils' 2.8.1.0.23 Using the GNU `binutils' (assembler, linker, and related tools) is preferable when possible, and they are required to build an ELF shared C library. Version 2.1 of the library uses ELF symbol versioning extensively. Support for this feature is incomplete or buggy before binutils 2.8.1.0.23, so you must use at least this version. * GNU `texinfo' 3.11 To correctly translate and install the Texinfo documentation you need this version of the `texinfo' package. Earlier versions do not understand all the tags used in the document, and the installation mechanisms for the info files is not present or works differently. On some Debian Linux based systems the `install-info' program supplied with the system works differently from the one we expect. You must therefore run `make install' like this: make INSTALL_INFO=/path/to/GNU/install-info install * GNU `awk' 3.0 Several files used during the build are generated using features of GNU `awk' that are not found in other implementations. If you change any of the `configure.in' files you will also need * GNU `autoconf' 2.12 and if you change any of the message translation files you will need * GNU `gettext' 0.10 or later You may also need these packages if you upgrade your source tree using patches, although we try to avoid this. Supported Configurations ======================== The GNU C Library currently supports configurations that match the following patterns: alpha-ANYTHING-linux arm-ANYTHING-linuxaout arm-ANYTHING-none iX86-ANYTHING-gnu iX86-ANYTHING-linux m68k-ANYTHING-linux powerpc-ANYTHING-linux sparc-ANYTHING-linux sparc64-ANYTHING-linux Former releases of this library (version 1.09.1 and perhaps earlier versions) used to run on the following configurations: alpha-dec-osf1 alpha-ANYTHING-linuxecoff iX86-ANYTHING-bsd4.3 iX86-ANYTHING-isc2.2 iX86-ANYTHING-isc3.N iX86-ANYTHING-sco3.2 iX86-ANYTHING-sco3.2v4 iX86-ANYTHING-sysv iX86-ANYTHING-sysv4 iX86-force_cpu386-none iX86-sequent-bsd i960-nindy960-none m68k-hp-bsd4.3 m68k-mvme135-none m68k-mvme136-none m68k-sony-newsos3 m68k-sony-newsos4 m68k-sun-sunos4.N mips-dec-ultrix4.N mips-sgi-irix4.N sparc-sun-solaris2.N sparc-sun-sunos4.N Since no one has volunteered to test and fix these configurations, they are not supported at the moment. They probably don't compile; they definitely don't work anymore. Porting the library is not hard. If you are interested in doing a port, please contact the glibc maintainers by sending electronic mail to . Each case of `iX86' can be `i386', `i486', `i586', or `i686'. All of those configurations produce a library that can run on any of these processors. The library will be optimized for the specified processor, but will not use instructions not available on all of them. While no other configurations are supported, there are handy aliases for these few. (These aliases work in other GNU software as well.) decstation hp320-bsd4.3 hp300bsd i486-gnu i586-linux i386-sco i386-sco3.2v4 i386-sequent-dynix i386-svr4 news sun3-sunos4.N sun3 sun4-solaris2.N sun4-sunos5.N sun4-sunos4.N sun4 Useful hints for the installation ================================= There are a some more or less obvious methods one should know when compiling GNU libc: * Better never compile in the source directory. Create a new directory and run the `configure' from there. Everything should happen automagically. * You can use the `-j' option of GNU make by changing the line specifying `PARALLELMAKE' in the Makefile generated during the configuration. It is not useful to start the `make' process using the `-j' option since this option is not propagated down to the sub-`make's. * If you made some changes after a complete build and only want to check these changes run `make' while specifying the list of subdirs it has to visit. make subdirs="nss elf" The above build run will only visit the subdirectories `nss' and `elf'. Beside this it updates the `libc' files itself. Reporting Bugs ============== There are probably bugs in the GNU C library. There are certainly errors and omissions in this manual. If you report them, they will get fixed. If you don't, no one will ever know about them and they will remain unfixed for all eternity, if not longer. To report a bug, first you must find it. Hopefully, this will be the hard part. Once you've found a bug, make sure it's really a bug. A good way to do this is to see if the GNU C library behaves the same way some other C library does. If so, probably you are wrong and the libraries are right (but not necessarily). If not, one of the libraries is probably wrong. Once you're sure you've found a bug, try to narrow it down to the smallest test case that reproduces the problem. In the case of a C library, you really only need to narrow it down to one library function call, if possible. This should not be too difficult. The final step when you have a simple test case is to report the bug. When reporting a bug, send your test case, the results you got, the results you expected, what you think the problem might be (if you've thought of anything), your system type, and the version of the GNU C library which you are using. Also include the files `config.status' and `config.make' which are created by running `configure'; they will be in whatever directory was current when you ran `configure'. If you think you have found some way in which the GNU C library does not conform to the ISO and POSIX standards (*note Standards and Portability::.), that is definitely a bug. Report it! Send bug reports to the Internet address using the `glibcbug' script which is installed by the GNU C library. If you have other problems with installation or use, please report those as well. If you are not sure how a function should behave, and this manual doesn't tell you, that's a bug in the manual. Report that too! If the function's behavior disagrees with the manual, then either the library or the manual has a bug, so report the disagreement. If you find any errors or omissions in this manual, please report them to the Internet address . If you refer to specific sections when reporting on the manual, please include the section names for easier identification.