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| author | Andreas Jaeger <aj@suse.de> | 2012-05-03 09:46:57 +0200 |
|---|---|---|
| committer | Andreas Jaeger <aj@suse.de> | 2012-05-03 09:46:57 +0200 |
| commit | 7ac30cc5f0460b72646abffee96584e063f96b5a (patch) | |
| tree | a355588263e608d007b06a98e5588897b70a02f9 /FAQ | |
| parent | e2dbf201abdfa13fc4035a1a8888ecec91bef44c (diff) | |
| download | glibc-7ac30cc5f0460b72646abffee96584e063f96b5a.tar.xz glibc-7ac30cc5f0460b72646abffee96584e063f96b5a.zip | |
Move FAQ to wiki
The FAQ is now at http://sourceware.org/glibc/wiki/FAQ and not
anymore part of the repository.
Diffstat (limited to 'FAQ')
| -rw-r--r-- | FAQ | 1976 |
1 files changed, 0 insertions, 1976 deletions
@@ -1,1976 +0,0 @@ - Frequently Asked Questions about the GNU C Library - -This document tries to answer questions a user might have when installing -and using glibc. Please make sure you read this before sending questions or -bug reports to the maintainers. - -The GNU C library is very complex. The installation process has not been -completely automated; there are too many variables. You can do substantial -damage to your system by installing the library incorrectly. Make sure you -understand what you are undertaking before you begin. - -If you have any questions you think should be answered in this document, -please let me know. - - --drepper@redhat.com - -~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - -1. Compiling glibc - -1.1. What systems does the GNU C Library run on? -1.2. What compiler do I need to build GNU libc? -1.3. When I try to compile glibc I get only error messages. - What's wrong? -1.4. Do I need a special linker or assembler? -1.5. Which compiler should I use for powerpc? -1.6. Which tools should I use for ARM? -1.7. Do I need some more things to compile the GNU C Library? -1.8. What version of the Linux kernel headers should be used? -1.9. The compiler hangs while building iconvdata modules. What's - wrong? -1.10. When I run `nm -u libc.so' on the produced library I still - find unresolved symbols. Can this be ok? -1.11. What are these `add-ons'? -1.12. My XXX kernel emulates a floating-point coprocessor for me. - Should I enable --with-fp? -1.13. When compiling GNU libc I get lots of errors saying functions - in glibc are duplicated in libgcc. -1.14. Why do I get messages about missing thread functions when I use - librt? I don't even use threads. -1.15. What's the problem with configure --enable-omitfp? -1.16. I get failures during `make check'. What should I do? -1.17. What is symbol versioning good for? Do I need it? -1.18. How can I compile on my fast ix86 machine a working libc for my slow - i386? After installing libc, programs abort with "Illegal - Instruction". -1.19. `make' complains about a missing dlfcn/libdl.so when building - malloc/libmemprof.so. How can I fix this? -1.20. Which tools should I use for MIPS? -1.21. Which compiler should I use for powerpc64? -1.22. `make' fails when running rpcgen the first time, - what is going on? How do I fix this? -1.23. Why do I get: - `#error "glibc cannot be compiled without optimization"', - when trying to compile GNU libc with GNU CC? - -2. Installation and configuration issues - -2.1. Can I replace the libc on my Linux system with GNU libc? -2.2. How do I configure GNU libc so that the essential libraries - like libc.so go into /lib and the other into /usr/lib? -2.3. How should I avoid damaging my system when I install GNU libc? -2.4. Do I need to use GNU CC to compile programs that will use the - GNU C Library? -2.5. When linking with the new libc I get unresolved symbols - `crypt' and `setkey'. Why aren't these functions in the - libc anymore? -2.6. When I use GNU libc on my Linux system by linking against - the libc.so which comes with glibc all I get is a core dump. -2.7. Looking through the shared libc file I haven't found the - functions `stat', `lstat', `fstat', and `mknod' and while - linking on my Linux system I get error messages. How is - this supposed to work? -2.8. When I run an executable on one system which I compiled on - another, I get dynamic linker errors. Both systems have the same - version of glibc installed. What's wrong? -2.9. How can I compile gcc 2.7.2.1 from the gcc source code using - glibc 2.x? -2.10. The `gencat' utility cannot process the catalog sources which - were used on my Linux libc5 based system. Why? -2.11. Programs using libc have their messages translated, but other - behavior is not localized (e.g. collating order); why? -2.12. I have set up /etc/nis.conf, and the Linux libc 5 with NYS - works great. But the glibc NIS+ doesn't seem to work. -2.13. I have killed ypbind to stop using NIS, but glibc - continues using NIS. -2.14. Under Linux/Alpha, I always get "do_ypcall: clnt_call: - RPC: Unable to receive; errno = Connection refused" when using NIS. -2.15. After installing glibc name resolving doesn't work properly. -2.16. How do I create the databases for NSS? -2.17. I have /usr/include/net and /usr/include/scsi as symlinks - into my Linux source tree. Is that wrong? -2.18. Programs like `logname', `top', `uptime' `users', `w' and - `who', show incorrect information about the (number of) - users on my system. Why? -2.19. After upgrading to glibc 2.1 with symbol versioning I get - errors about undefined symbols. What went wrong? -2.20. When I start the program XXX after upgrading the library - I get - XXX: Symbol `_sys_errlist' has different size in shared - object, consider re-linking - Why? What should I do? -2.21. What do I need for C++ development? -2.22. Even statically linked programs need some shared libraries - which is not acceptable for me. What can I do? -2.23. I just upgraded my Linux system to glibc and now I get - errors whenever I try to link any program. -2.24. When I use nscd the machine freezes. -2.25. I need lots of open files. What do I have to do? -2.26. How do I get the same behavior on parsing /etc/passwd and - /etc/group as I have with libc5 ? -2.27. What needs to be recompiled when upgrading from glibc 2.0 to glibc - 2.1? -2.28. Why is extracting files via tar so slow? -2.29. Compiling programs I get parse errors in libio.h (e.g. "parse error - before `_IO_seekoff'"). How should I fix this? -2.30. After upgrading to glibc 2.1, libraries that were compiled against - glibc 2.0.x don't work anymore. -2.31. What happened to the Berkeley DB libraries? Can I still use db - in /etc/nsswitch.conf? -2.32. What has do be done when upgrading to glibc 2.2? -2.33. The makefiles want to do a CVS commit. -2.34. When compiling C++ programs, I get a compilation error in streambuf.h. -2.35. When recompiling GCC, I get compilation errors in libio. -2.36. Why shall glibc never get installed on GNU/Linux systems in -/usr/local? -2.37. When recompiling GCC, I get compilation errors in libstdc++. - -3. Source and binary incompatibilities, and what to do about them - -3.1. I expect GNU libc to be 100% source code compatible with - the old Linux based GNU libc. Why isn't it like this? -3.2. Why does getlogin() always return NULL on my Linux box? -3.3. Where are the DST_* constants found in <sys/time.h> on many - systems? -3.4. The prototypes for `connect', `accept', `getsockopt', - `setsockopt', `getsockname', `getpeername', `send', - `sendto', and `recvfrom' are different in GNU libc from - any other system I saw. This is a bug, isn't it? -3.5. On Linux I've got problems with the declarations in Linux - kernel headers. -3.6. I don't include any kernel headers myself but the compiler - still complains about redeclarations of types in the kernel - headers. -3.7. Why don't signals interrupt system calls anymore? -3.8. I've got errors compiling code that uses certain string - functions. Why? -3.9. I get compiler messages "Initializer element not constant" with - stdin/stdout/stderr. Why? -3.10. I can't compile with gcc -traditional (or - -traditional-cpp). Why? -3.11. I get some errors with `gcc -ansi'. Isn't glibc ANSI compatible? -3.12. I can't access some functions anymore. nm shows that they do - exist but linking fails nevertheless. -3.13. When using the db-2 library which comes with glibc is used in - the Perl db modules the testsuite is not passed. This did not - happen with db-1, gdbm, or ndbm. -3.14. The pow() inline function I get when including <math.h> is broken. - I get segmentation faults when I run the program. -3.15. The sys/sem.h file lacks the definition of `union semun'. -3.16. Why has <netinet/ip_fw.h> disappeared? -3.17. I get floods of warnings when I use -Wconversion and include - <string.h> or <math.h>. -3.18. After upgrading to glibc 2.1, I receive errors about - unresolved symbols, like `_dl_initial_searchlist' and can not - execute any binaries. What went wrong? -3.19. bonnie reports that char i/o with glibc 2 is much slower than with - libc5. What can be done? -3.20. Programs compiled with glibc 2.1 can't read db files made with glibc - 2.0. What has changed that programs like rpm break? -3.21. Autoconf's AC_CHECK_FUNC macro reports that a function exists, but - when I try to use it, it always returns -1 and sets errno to ENOSYS. -3.22. My program segfaults when I call fclose() on the FILE* returned - from setmntent(). Is this a glibc bug? -3.23. I get "undefined reference to `atexit'" - -4. Miscellaneous - -4.1. After I changed configure.in I get `Autoconf version X.Y. - or higher is required for this script'. What can I do? -4.2. When I try to compile code which uses IPv6 headers and - definitions on my Linux 2.x.y system I am in trouble. - Nothing seems to work. -4.3. When I set the timezone by setting the TZ environment variable - to EST5EDT things go wrong since glibc computes the wrong time - from this information. -4.4. What other sources of documentation about glibc are available? -4.5. The timezone string for Sydney/Australia is wrong since even when - daylight saving time is in effect the timezone string is EST. -4.6. I've build make 3.77 against glibc 2.1 and now make gets - segmentation faults. -4.7. Why do so many programs using math functions fail on my AlphaStation? -4.8. The conversion table for character set XX does not match with -what I expect. -4.9. How can I find out which version of glibc I am using in the moment? -4.10. Context switching with setcontext() does not work from within - signal handlers. - - -~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - -1. Compiling glibc - -1.1. What systems does the GNU C Library run on? - -{UD} This is difficult to answer. The file `README' lists the architectures -GNU libc was known to run on *at some time*. This does not mean that it -still can be compiled and run on them now. - -The systems glibc is known to work on as of this release, and most probably -in the future, are: - - *-*-gnu GNU Hurd - i[3456]86-*-linux-gnu Linux-2.x on Intel - m68k-*-linux-gnu Linux-2.x on Motorola 680x0 - alpha*-*-linux-gnu Linux-2.x on DEC Alpha - powerpc-*-linux-gnu Linux and MkLinux on PowerPC systems - powerpc64-*-linux-gnu Linux-2.4+ on 64-bit PowerPC systems - sparc-*-linux-gnu Linux-2.x on SPARC - sparc64-*-linux-gnu Linux-2.x on UltraSPARC - arm-*-none ARM standalone systems - arm-*-linux Linux-2.x on ARM - arm-*-linuxaout Linux-2.x on ARM using a.out binaries - mips*-*-linux-gnu Linux-2.x on MIPS - ia64-*-linux-gnu Linux-2.x on ia64 - s390-*-linux-gnu Linux-2.x on IBM S/390 - s390x-*-linux-gnu Linux-2.x on IBM S/390 64-bit - cris-*-linux-gnu Linux-2.4+ on CRIS - -Ports to other Linux platforms are in development, and may in fact work -already, but no one has sent us success reports for them. Currently no -ports to other operating systems are underway, although a few people have -expressed interest. - -If you have a system not listed above (or in the `README' file) and you are -really interested in porting it, see the GNU C Library web pages to learn -how to start contributing: - - http://www.gnu.org/software/libc/resources.html - - -1.2. What compiler do I need to build GNU libc? - -{UD} You must use GNU CC to compile GNU libc. A lot of extensions of GNU CC -are used to increase portability and speed. - -GNU CC is found, like all other GNU packages, on - - ftp://ftp.gnu.org/pub/gnu - -and the many mirror sites. ftp.gnu.org is always overloaded, so try to find -a local mirror first. - -You should always try to use the latest official release. Older versions -may not have all the features GNU libc requires. The current releases of -gcc (3.2 or newer) should work with the GNU C library (for MIPS see question 1.20). - -Please note that gcc 2.95 and 2.95.x cannot compile glibc on Alpha due to -problems in the complex float support. - - -1.3. When I try to compile glibc I get only error messages. - What's wrong? - -{UD} You definitely need GNU make to build GNU libc. No other make -program has the needed functionality. - -We recommend version GNU make version 3.79 or newer. Older versions have -bugs and/or are missing features. - - -1.4. Do I need a special linker or assembler? - -{ZW} If you want a shared library, you need a linker and assembler that -understand all the features of ELF, including weak and versioned symbols. -The static library can be compiled with less featureful tools, but lacks key -features such as NSS. - -For Linux or Hurd, you want binutils 2.13 or higher. These are the only -versions we've tested and found reliable. Other versions may work but we -don't recommend them, especially not when C++ is involved. - -Other operating systems may come with system tools that have all the -necessary features, but this is moot because glibc hasn't been ported to -them. - - -1.5. Which compiler should I use for powerpc? - -{} Removed. Does not apply anymore. - - -1.6. Which tools should I use for ARM? - -{} Removed. Does not apply anymore. - - -1.7. Do I need some more things to compile the GNU C Library? - -{UD} Yes, there are some more :-). - -* GNU gettext. This package contains the tools needed to construct - `message catalog' files containing translated versions of system - messages. See ftp://ftp.gnu.org/pub/gnu or better any mirror - site. (We distribute compiled message catalogs, but they may not be - updated in patches.) - -* Some files are built with special tools. E.g., files ending in .gperf - need a `gperf' program. The GNU version (now available in a separate - package, formerly only as part of libg++) is known to work while some - vendor versions do not. - - You should not need these tools unless you change the source files. - -* Perl 5 is needed if you wish to test an installation of GNU libc - as the primary C library. - -* When compiling for Linux, the header files of the Linux kernel must - be available to the compiler as <linux/*.h> and <asm/*.h>. - -* lots of disk space (~400MB for i?86-linux; more for RISC platforms). - -* plenty of time. Compiling just the shared and static libraries for - 35mins on a 2xPIII@550Mhz w/ 512MB RAM. On a 2xUltraSPARC-II@360Mhz - w/ 1GB RAM it takes about 14 minutes. Multiply this by 1.5 or 2.0 - if you build profiling and/or the highly optimized version as well. - For Hurd systems times are much higher. - - You should avoid compiling in a NFS mounted filesystem. This is - very slow. - - James Troup <J.J.Troup@comp.brad.ac.uk> reports a compile time for - an earlier (and smaller!) version of glibc of 45h34m for a full build - (shared, static, and profiled) on Atari Falcon (Motorola 68030 @ 16 Mhz, - 14 Mb memory) and Jan Barte <yann@plato.uni-paderborn.de> reports - 22h48m on Atari TT030 (Motorola 68030 @ 32 Mhz, 34 Mb memory) - - A full build of the PowerPC library took 1h on a PowerPC 750@400Mhz w/ - 64MB of RAM, and about 9h on a 601@60Mhz w/ 72Mb. - - -1.8. What version of the Linux kernel headers should be used? - -{AJ,UD} The headers from the most recent Linux kernel should be used. The -headers used while compiling the GNU C library and the kernel binary used -when using the library do not need to match. The GNU C library runs without -problems on kernels that are older than the kernel headers used. The other -way round (compiling the GNU C library with old kernel headers and running -on a recent kernel) does not necessarily work. For example you can't use -new kernel features if you used old kernel headers to compile the GNU C -library. - -{ZW} Even if you are using a 2.0 kernel on your machine, we recommend you -compile GNU libc with 2.2 kernel headers. That way you won't have to -recompile libc if you ever upgrade to kernel 2.2. To tell libc which -headers to use, give configure the --with-headers switch -(e.g. --with-headers=/usr/src/linux-2.2.0/include). - -Note that you must configure the 2.2 kernel if you do this, otherwise libc -will be unable to find <linux/version.h>. Just change the current directory -to the root of the 2.2 tree and do `make include/linux/version.h'. - - -1.9. The compiler hangs while building iconvdata modules. What's - wrong? - -{} Removed. Does not apply anymore. - - -1.10. When I run `nm -u libc.so' on the produced library I still - find unresolved symbols. Can this be ok? - -{UD} Yes, this is ok. There can be several kinds of unresolved symbols: - -* magic symbols automatically generated by the linker. These have names - like __start_* and __stop_* - -* symbols starting with _dl_* come from the dynamic linker - -* weak symbols, which need not be resolved at all (fabs for example) - -Generally, you should make sure you find a real program which produces -errors while linking before deciding there is a problem. - - -1.11. What are these `add-ons'? - -{UD} To avoid complications with export rules or external source code some -optional parts of the libc are distributed as separate packages, e.g., the -linuxthreads package. - -To use these packages as part of GNU libc, just unpack the tarfiles in the -libc source directory and tell the configuration script about them using the ---enable-add-ons option. If you give just --enable-add-ons configure tries -to find all the add-on packages in your source tree. This may not work. If -it doesn't, or if you want to select only a subset of the add-ons, give a -comma-separated list of the add-ons to enable: - - configure --enable-add-ons=linuxthreads - -for example. - -Add-ons can add features (including entirely new shared libraries), override -files, provide support for additional architectures, and just about anything -else. The existing makefiles do most of the work; only some few stub rules -must be written to get everything running. - -Most add-ons are tightly coupled to a specific GNU libc version. Please -check that the add-ons work with the GNU libc. For example the linuxthreads -add-on has the same numbering scheme as the libc and will in general only -work with the corresponding libc. - -{AJ} With glibc 2.2 the crypt add-on and with glibc 2.1 the localedata -add-on have been integrated into the normal glibc distribution, crypt and -localedata are therefore not anymore add-ons. - - -1.12. My XXX kernel emulates a floating-point coprocessor for me. - Should I enable --with-fp? - -{ZW} An emulated FPU is just as good as a real one, as far as the C library -is concerned. You only need to say --without-fp if your machine has no way -to execute floating-point instructions. - -People who are interested in squeezing the last drop of performance -out of their machine may wish to avoid the trap overhead, but this is -far more trouble than it's worth: you then have to compile -*everything* this way, including the compiler's internal libraries -(libgcc.a for GNU C), because the calling conventions change. - - -1.13. When compiling GNU libc I get lots of errors saying functions - in glibc are duplicated in libgcc. - -{EY} This is *exactly* the same problem that I was having. The problem was -due to the fact that configure didn't correctly detect that the linker flag ---no-whole-archive was supported in my linker. In my case it was because I -had run ./configure with bogus CFLAGS, and the test failed. - -One thing that is particularly annoying about this problem is that once this -is misdetected, running configure again won't fix it unless you first delete -config.cache. - -{UD} Starting with glibc-2.0.3 there should be a better test to avoid some -problems of this kind. The setting of CFLAGS is checked at the very -beginning and if it is not usable `configure' will bark. - - -1.14. Why do I get messages about missing thread functions when I use - librt? I don't even use threads. - -{UD} In this case you probably mixed up your installation. librt uses -threads internally and has implicit references to the thread library. -Normally these references are satisfied automatically but if the thread -library is not in the expected place you must tell the linker where it is. -When using GNU ld it works like this: - - gcc -o foo foo.c -Wl,-rpath-link=/some/other/dir -lrt - -The `/some/other/dir' should contain the thread library. `ld' will use the -given path to find the implicitly referenced library while not disturbing -any other link path. - - -1.15. What's the problem with configure --enable-omitfp? - -{} Removed. Does not apply anymore. - - -1.16. I get failures during `make check'. What should I do? - -{AJ} The testsuite should compile and run cleanly on your system; every -failure should be looked into. Depending on the failures, you probably -should not install the library at all. - -You should consider reporting it in bugzilla -<http://sourceware.org/bugzilla/> providing as much detail as possible. -If you run a test directly, please remember to set up the environment -correctly. You want to test the compiled library - and not your installed -one. The best way is to copy the exact command line which failed and run -the test from the subdirectory for this test in the sources. - -There are some failures which are not directly related to the GNU libc: -- Some compilers produce buggy code. No compiler gets single precision - complex numbers correct on Alpha. Otherwise, gcc-3.2 should be ok. -- The kernel might have bugs. For example on Linux/Alpha 2.0.34 the - floating point handling has quite a number of bugs and therefore most of - the test cases in the math subdirectory will fail. Linux 2.2 has - fixes for the floating point support on Alpha. The Linux/SPARC kernel has - also some bugs in the FPU emulation code (as of Linux 2.2.0). -- Other tools might have problems. For example bash 2.03 gives a - segmentation fault running the tst-rpmatch.sh test script. - - -1.17. What is symbol versioning good for? Do I need it? - -{AJ} Symbol versioning solves problems that are related to interface -changes. One version of an interface might have been introduced in a -previous version of the GNU C library but the interface or the semantics of -the function has been changed in the meantime. For binary compatibility -with the old library, a newer library needs to still have the old interface -for old programs. On the other hand, new programs should use the new -interface. Symbol versioning is the solution for this problem. The GNU -libc version 2.1 uses symbol versioning by default if the installed binutils -supports it. - -We don't advise building without symbol versioning, since you lose binary -compatibility - forever! The binary compatibility you lose is not only -against the previous version of the GNU libc (version 2.0) but also against -all future versions. - - -1.18. How can I compile on my fast ix86 machine a working libc for my slow - i386? After installing libc, programs abort with "Illegal - Instruction". - -{AJ} glibc and gcc might generate some instructions on your machine that -aren't available on i386. You've got to tell glibc that you're configuring -for i386 with adding i386 as your machine, for example: - - ../configure --prefix=/usr i386-pc-linux-gnu - -And you need to tell gcc to only generate i386 code, just add `-mcpu=i386' -(just -m386 doesn't work) to your CFLAGS. - -{UD} This applies not only to the i386. Compiling on a i686 for any older -model will also fail if the above methods are not used. - - -1.19. `make' complains about a missing dlfcn/libdl.so when building - malloc/libmemprof.so. How can I fix this? - -{AJ} Older make version (<= 3.78.90) have a bug which was hidden by a bug in -glibc (<= 2.1.2). You need to upgrade make to a newer or fixed version. - -After upgrading make, you should remove the file sysd-sorted in your build -directory. The problem is that the broken make creates a wrong order for -one list in that file. The list has to be recreated with the new make - -which happens if you remove the file. - -You might encounter this bug also in other situations where make scans -directories. I strongly advise to upgrade your make version to 3.79 or -newer. - - -1.20. Which tools should I use for MIPS? - -{AJ} You should use the current development version of gcc 3.2 or newer from -CVS. - -You need also recent binutils, anything before and including 2.11 will not -work correctly. Either try the Linux binutils 2.11.90.0.5 from HJ Lu or the -current development version of binutils from CVS. - -Please note that `make check' might fail for a number of the math tests -because of problems of the FPU emulation in the Linux kernel (the MIPS FPU -doesn't handle all cases and needs help from the kernel). - - -1.21. Which compiler should I use for powerpc64? - -{SM} You want to use at least gcc 3.2 (together with the right versions -of all the other tools, of course). - - -1.22. `make' fails when running rpcgen the first time, - what is going on? How do I fix this? - -{CO} The first invocation of rpcgen is also the first use of the recently -compiled dynamic loader. If there is any problem with the dynamic loader -it will more than likely fail to run rpcgen properly. This could be due to -any number of problems. - -The only real solution is to debug the loader and determine the problem -yourself. Please remember that for each architecture there may be various -patches required to get glibc HEAD into a runnable state. The best course -of action is to determine if you have all the required patches. - - -1.23. Why do I get: - `#error "glibc cannot be compiled without optimization"', - when trying to compile GNU libc with GNU CC? - -{AJ,CO} There are a couple of reasons why the GNU C library will not work -correctly if it is not complied with optimzation. - -In the early startup of the dynamic loader (_dl_start), before -relocation of the PLT, you cannot make func |
