If you have any questions you think should be answered in this document,
please let me know.
- --drepper@cygnus.com
+ --drepper@redhat.com
\f
? Compiling glibc
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
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
expressed interest.
If you have a system not listed above (or in the `README' file) and you are
-really interested in porting it, contact
+really interested in porting it, see the GNU C Library web pages to learn
+how to start contributing:
- <bug-glibc@gnu.org>
+ http://www.gnu.org/software/libc/resources.html
??binsize What compiler do I need to build GNU libc?
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
-egcs (1.0.3 and 1.1.1) should work with the GNU C library (for powerpc see
-?powerpc; for ARM see ?arm; for MIPS see ?mips).
-
-While the GNU CC should be able to compile glibc it is nevertheless adviced
-to use EGCS. Comparing the sizes of glibc on Intel compiled with a recent
-EGCS and gcc 2.8.1 shows this:
-
- text data bss dec hex filename
- egcs-2.93.10 862897 15944 12824 891665 d9b11 libc.so
- gcc-2.8.1 959965 16468 12152 988585 f15a9 libc.so
-
-Make up your own decision.
-
-GNU CC versions 2.95 and above are derived from egcs, and they may do even
-better.
+gcc (3.2 or newer) should work with the GNU C library (for MIPS see ?mips).
Please note that gcc 2.95 and 2.95.x cannot compile glibc on Alpha due to
problems in the complex float support.
The static library can be compiled with less featureful tools, but lacks key
features such as NSS.
-For Linux or Hurd, you want binutils 2.8.1.0.23, 2.9.1, or 2.9.1.0.15 or
-higher. These are the only versions we've tested and found reliable. Other
-versions after 2.8.1.0.23 may work but we don't recommend them, especially
-not when C++ is involved. Earlier versions do not work at all.
+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
??powerpc Which compiler should I use for powerpc?
-{GK} You want to use at least gcc 2.95 (together with the right versions
-of all the other tools, of course). See also question ?excpt.
+{} Removed. Does not apply anymore.
??arm Which tools should I use for ARM?
-{PB} You should use egcs 1.1 or a later version. For ELF systems some
-changes are needed to the compiler; a patch against egcs-1.1.x can be found
-at:
-
-<ftp://ftp.netwinder.org/users/p/philb/egcs-1.1.1pre2-diff-981126>
-
-Binutils 2.9.1.0.16 or later is also required.
+{} Removed. Does not apply anymore.
?? Do I need some more things to compile the GNU C Library?
`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.) Please note that the required minimal version
- (0.10.35) of gettext is alpha software and available from
- ftp://alpha.gnu.org/gnu .
+ 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
* lots of disk space (~400MB for i?86-linux; more for RISC platforms).
* plenty of time. Compiling just the shared and static libraries for
- i?86-linux takes approximately 1h on an AMD-K6@225MHz w/ 96MB of RAM,
- 45mins on a Celeron@400MHz w/ 128MB, and 55mins on a Alpha@533MHz w/ 256MB.
- 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.
+ 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 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)
+ 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.
- If you have some more measurements let me know.
-
?? What version of the Linux kernel headers should be used?
{AJ,UD} The headers from the most recent Linux kernel should be used. The
?? The compiler hangs while building iconvdata modules. What's
wrong?
-{ZW} This is a problem with old versions of GCC. Initialization of large
-static arrays is very slow. The compiler will eventually finish; give it
-time.
-
-The problem is fixed in egcs 1.1.
+{} Removed. Does not apply anymore.
?? When I run `nm -u libc.so' on the produced library I still
find unresolved symbols. Can this be ok?
?? What's the problem with configure --enable-omitfp?
-{AJ} When --enable-omitfp is set the libraries are built without frame
-pointers. Some compilers produce buggy code for this model and therefore we
-don't advise using it at the moment.
-
-If you use --enable-omitfp, you're on your own. If you encounter problems
-with a library that was build this way, we advise you to rebuild the library
-without --enable-omitfp. If the problem vanishes consider tracking the
-problem down and report it as compiler failure.
-
-Since a library built with --enable-omitfp is undebuggable on most systems,
-debuggable libraries are also built - you can use them by appending "_g" to
-the library names.
-
-The compilation of these extra libraries and the compiler optimizations slow
-down the build process and need more disk space.
+{} Removed. Does not apply anymore.
?? I get failures during `make check'. What should I do?
failure should be looked into. Depending on the failures, you probably
should not install the library at all.
-You should consider using the `glibcbug' script to report the failure,
-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.
+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, the egcs 1.1 release should be
- ok; gcc 2.8.1 might cause some failures; gcc 2.7.2.x is so buggy that
- explicit checks have been used so that you can't build with it.
+ 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
??mips Which tools should I use for MIPS?
-{AJ} You should use the current development version of gcc 2.97 from CVS.
-gcc 2.95.x does not work correctly on mips-linux.
+{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).
+
+
+??powerpc64 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).
+
+?? `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.
+
+?? Why do I get:
+ `#error "glibc cannot be compiled without optimization"',
+ when trying to compile GNU libc with GNU CC?
-You need also recent binutils, anything before and including 2.10 will not
-work correctly. Either try the Linux binutils 2.10.0.33 from HJ Lu or the
-current development version from CVS of binutils.
+{AJ,CO} There are a couple of reasons why the GNU C library will not work
+correctly if it is not complied with optimzation.
-For details check also my page <http://www.suse.de/~aj/glibc-mips.html>.
+In the early startup of the dynamic loader (_dl_start), before
+relocation of the PLT, you cannot make function calls. You must inline
+the functions you will use during early startup, or call compiler
+builtins (__builtin_*).
+
+Without optimizations enabled GNU CC will not inline functions. The
+early startup of the dynamic loader will make function calls via an
+unrelocated PLT and crash.
+
+Without auditing the dynamic linker code it would be difficult to remove
+this requirement.
+
+Another reason is that nested functions must be inlined in many cases to
+avoid executable stacks.
+
+In practice there is no reason to compile without optimizations, therefore
+we require that GNU libc be compiled with optimizations enabled.
? Installation and configuration issues
libc anymore?
-Removed. Does not apply anymore.
+{} Removed. Does not apply anymore.
?? 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.
Version 2.7.2.3 does and future versions of GCC will automatically
provide the correct specs.
-?? Looking through the shared libc file I haven't found the
+??nonsh 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?
glibc 2.x?
{AJ} There's only correct support for glibc 2.0.x in gcc 2.7.2.3 or later.
-But you should get at least gcc 2.8.1 or egcs 1.1 (or later versions)
-instead.
+But you should get at least gcc 2.95.3 (or later versions) anyway
?? The `gencat' utility cannot process the catalog sources which
were used on my Linux libc5 based system. Why?
-----------------------------------------------------------------------
# Change catalog source in Linux specific format to standard XPG format.
-# Ulrich Drepper <drepper@cygnus.com>, 1996.
+# Ulrich Drepper <drepper@redhat.com>, 1996.
#
/^\$ #/ {
h
`db-Makefile' in the subdirectory `nss' and you can call it with `make -f
db-Makefile'. Please note that not all services are capable of using a
database. Currently passwd, group, ethers, protocol, rpc, services shadow
-and netgroup are implemented. See also question ?nssdb.
+and netgroup are implemented. See also ?nssdb.
?? I have /usr/include/net and /usr/include/scsi as symlinks
into my Linux source tree. Is that wrong?
{AJ} You might get the following errors when upgrading to glibc 2.1:
In file included from /usr/include/stdio.h:57,
- from ...
+ from ...
/usr/include/libio.h:335: parse error before `_IO_seekoff'
/usr/include/libio.h:335: parse error before `_G_off64_t'
/usr/include/libio.h:336: parse error before `_IO_seekpos'
If it has been in use, it should be switched off.
- Programs using IPv6 have to be recompiled due to incompatible changes in
sockaddr_in6 by the IPv6 working group.
-- The Berkeley db libraries have been removed (for details see ??nssdb).
+- The Berkeley db libraries have been removed (for details see ?nssdb).
- The format of the locale files has changed, all locales should be
regenerated with localedef. All statically linked applications which use
i18n should be recompiled, otherwise they'll not be localized.
Please read also the NEWS file which is the authoritative source for this
and gives more details for some topics.
+?? The makefiles want to do a CVS commit.
+
+{} Removed. Does not apply anymore.
+
+?? When compiling C++ programs, I get a compilation error in streambuf.h.
+
+{BH} You are using g++ 2.95.2? After upgrading to glibc 2.2, you need to
+apply a patch to the include files in /usr/include/g++, because the fpos_t
+type has changed in glibc 2.2. The patch is at
+
+ http://www.haible.de/bruno/gccinclude-glibc-2.2-compat.diff
+
+?? When recompiling GCC, I get compilation errors in libio.
+
+{BH} You are trying to recompile gcc 2.95.2? Use gcc 2.95.3 instead.
+This version is needed because the fpos_t type and a few libio internals
+have changed in glibc 2.2, and gcc 2.95.3 contains a corresponding patch.
+
+?? Why shall glibc never get installed on GNU/Linux systems in
+/usr/local?
+
+{AJ} The GNU C compiler treats /usr/local/include and /usr/local/lib in a
+special way, these directories will be searched before the system
+directories. Since on GNU/Linux the system directories /usr/include and
+/usr/lib contain a --- possibly different --- version of glibc and mixing
+certain files from different glibc installations is not supported and will
+break, you risk breaking your complete system. If you want to test a glibc
+installation, use another directory as argument to --prefix. If you like to
+install this glibc version as default version, overriding the existing one,
+use --prefix=/usr and everything will go in the right places.
+
+?? When recompiling GCC, I get compilation errors in libstdc++.
+
+{BH} You are trying to recompile gcc 3.2? You need to patch gcc 3.2,
+because some last minute changes were made in glibc 2.3 which were not
+known when gcc 3.2 was released. The patch is at
+
+ http://www.haible.de/bruno/gcc-3.2-glibc-2.3-compat.diff
? Source and binary incompatibilities, and what to do about them
the Perl db modules the testsuite is not passed. This did not
happen with db-1, gdbm, or ndbm.
-Removed. Does not apply anymore.
+{} Removed. Does not apply anymore.
?? The pow() inline function I get when including <math.h> is broken.
I get segmentation faults when I run the program.
?? Programs compiled with glibc 2.1 can't read db files made with glibc
2.0. What has changed that programs like rpm break?
-Removed. Does not apply anymore.
+{} Removed. Does not apply anymore.
?? 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.
won't always work. Unfortunately, for compatibility reasons, we can't
change the return type of setmntent() to something other than FILE *.
+?? I get "undefined reference to `atexit'"
+
+{UD} This means that your installation is somehow broken. The situation is
+the same as for 'stat', 'fstat', etc (see ?nonsh). Investigate why the
+linker does not pick up libc_nonshared.a.
+
+If a similar message is issued at runtime this means that the application or
+DSO is not linked against libc. This can cause problems since 'atexit' is
+not exported anymore.
+
? Miscellaneous
??make I've build make 3.77 against glibc 2.1 and now make gets
segmentation faults.
-Removed. Does not apply anymore, use make 3.79 or newer.
+{} Removed. Does not apply anymore, use make 3.79 or newer.
?? Why do so many programs using math functions fail on my AlphaStation?
if it cannot directly map a character this is a perfectly good solution
since the semantics and appearance of the character does not change.
+?? How can I find out which version of glibc I am using in the moment?
+
+{UD} If you want to find out about the version from the command line simply
+run the libc binary. This is probably not possible on all platforms but
+where it is simply locate the libc DSO and start it as an application. On
+Linux like
+
+ /lib/libc.so.6
+
+This will produce all the information you need.
+
+What always will work is to use the API glibc provides. Compile and run the
+following little program to get the version information:
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+#include <stdio.h>
+#include <gnu/libc-version.h>
+int main (void) { puts (gnu_get_libc_version ()); return 0; }
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This interface can also obviously be used to perform tests at runtime if
+this should be necessary.
+
+?? Context switching with setcontext() does not work from within
+ signal handlers.
+
+{DMT} The Linux implementations (IA-64, S390 so far) of setcontext()
+supports synchronous context switches only. There are several reasons for
+this:
+
+- UNIX provides no other (portable) way of effecting a synchronous
+ context switch (also known as co-routine switch). Some versions
+ support this via setjmp()/longjmp() but this does not work
+ universally.
+
+- As defined by the UNIX '98 standard, the only way setcontext()
+ could trigger an asychronous context switch is if this function
+ were invoked on the ucontext_t pointer passed as the third argument
+ to a signal handler. But according to draft 5, XPG6, XBD 2.4.3,
+ setcontext() is not among the set of routines that may be called
+ from a signal handler.
+
+- If setcontext() were to be used for asynchronous context switches,
+ all kinds of synchronization and re-entrancy issues could arise and
+ these problems have already been solved by real multi-threading
+ libraries (e.g., POSIX threads or Linux threads).
+
+- Synchronous context switching can be implemented entirely in
+ user-level and less state needs to be saved/restored than for an
+ asynchronous context switch. It is therefore useful to distinguish
+ between the two types of context switches. Indeed, some
+ application vendors are known to use setcontext() to implement
+ co-routines on top of normal (heavier-weight) pre-emptable threads.
+
+It should be noted that if someone was dead-bent on using setcontext()
+on the third arg of a signal handler, then IA-64 Linux could support
+this via a special version of sigaction() which arranges that all
+signal handlers start executing in a shim function which takes care of
+saving the preserved registers before calling the real signal handler
+and restoring them afterwards. In other words, we could provide a
+compatibility layer which would support setcontext() for asynchronous
+context switches. However, given the arguments above, I don't think
+that makes sense. setcontext() provides a decent co-routine interface
+and we should just discourage any asynchronous use (which just calls
+for trouble at any rate).
+
+
\f
Answers were given by:
-{UD} Ulrich Drepper, <drepper@cygnus.com>
-{DMT} David Mosberger-Tang, <davidm@AZStarNet.com>
+{UD} Ulrich Drepper, <drepper@redhat.com>
+{DMT} David Mosberger-Tang, <davidm@hpl.hp.com>
{RM} Roland McGrath, <roland@gnu.org>
{AJ} Andreas Jaeger, <aj@suse.de>
{EY} Eric Youngdale, <eric@andante.jic.com>
{MK} Mark Kettenis, <kettenis@phys.uva.nl>
{ZW} Zack Weinberg, <zack@rabi.phys.columbia.edu>
{TK} Thorsten Kukuk, <kukuk@suse.de>
-{GK} Geoffrey Keating, <geoffk@ozemail.com.au>
+{GK} Geoffrey Keating, <geoffk@redhat.com>
{HJ} H.J. Lu, <hjl@gnu.org>
{CG} Cristian Gafton, <gafton@redhat.com>
-{AO} Alexandre Oliva, <oliva@lsd.ic.unicamp.br>
+{AO} Alexandre Oliva, <aoliva@redhat.com>
+{BH} Bruno Haible, <haible@clisp.cons.org>
+{SM} Steven Munroe, <sjmunroe@us.ibm.com>
+{CO} Carlos O'Donell, <carlos@systemhalted.org>
\f
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