glibc/INSTALL
Andreas K. Hüttel 068b04eaed
INSTALL, install.texi: minor updates, regenerate
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
2024-01-31 00:13:43 +01:00

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Installing the GNU C Library
****************************
Before you do anything else, you should read the FAQ at
<https://sourceware.org/glibc/wiki/FAQ>. It answers common questions
and describes problems you may experience with compilation and
installation.
You will need recent versions of several GNU tools: definitely GCC
and GNU Make, and possibly others. *Note Tools for Compilation::,
below.
Configuring and compiling the GNU C Library
===========================================
The GNU C Library cannot be compiled in the source directory. You must
build it in a separate build directory. For example, if you have
unpacked the GNU C Library sources in /src/gnu/glibc-VERSION, create a
directory /src/gnu/glibc-build to put the object files in. This
allows removing the whole build directory in case an error occurs, which
is the safest way to get a fresh start and should always be done.
From your object directory, run the shell script configure located
at the top level of the source tree. In the scenario above, youd type
$ ../glibc-VERSION/configure ARGS...
Please note that even though youre building in a separate build
directory, the compilation may need to create or modify files and
directories in the source directory.
configure takes many options, but the only one that is usually
mandatory is --prefix. This option tells configure where you want
the GNU C Library installed. This defaults to /usr/local, but the
normal setting to install as the standard system library is
--prefix=/usr for GNU/Linux systems and --prefix= (an empty prefix)
for GNU/Hurd systems.
It may also be useful to pass CC=COMPILER and CFLAGS=FLAGS
arguments to configure. CC selects the C compiler that will be
used, and CFLAGS sets optimization options for the compiler. Any
compiler options required for all compilations, such as options
selecting an ABI or a processor for which to generate code, should be
included in CC. Options that may be overridden by the GNU C Library
build system for particular files, such as for optimization and
debugging, should go in CFLAGS. The default value of CFLAGS is -g
-O2, and the GNU C Library cannot be compiled without optimization, so
if CFLAGS is specified it must enable optimization. For example:
$ ../glibc-VERSION/configure CC="gcc -m32" CFLAGS="-O3"
The following list describes all of the available options for
configure:
--prefix=DIRECTORY
Install machine-independent data files in subdirectories of
DIRECTORY. The default is to install in /usr/local.
--exec-prefix=DIRECTORY
Install the library and other machine-dependent files in
subdirectories of DIRECTORY. The default is to the --prefix
directory if that option is specified, or /usr/local otherwise.
--with-headers=DIRECTORY
Look for kernel header files in DIRECTORY, not /usr/include. The
GNU C Library needs information from the kernels header files
describing the interface to the kernel. The GNU C Library will
normally look in /usr/include for them, but if you specify this
option, it will look in DIRECTORY instead.
This option is primarily of use on a system where the headers in
/usr/include come from an older version of the GNU C Library.
Conflicts can occasionally happen in this case. You can also use
this option if you want to compile the GNU C Library with a newer
set of kernel headers than the ones found in /usr/include.
--enable-kernel=VERSION
This option is currently only useful on GNU/Linux systems. The
VERSION parameter should have the form X.Y.Z and describes the
smallest version of the Linux kernel the generated library is
expected to support. The higher the VERSION number is, the less
compatibility code is added, and the faster the code gets.
--with-binutils=DIRECTORY
Use the binutils (assembler and linker) in DIRECTORY, not the
ones the C compiler would default to. You can use this option if
the default binutils on your system cannot deal with all the
constructs in the GNU C Library. In that case, configure will
detect the problem and suppress these constructs, so that the
library will still be usable, but functionality may be lost—for
example, you cant build a shared libc with old binutils.
--with-nonshared-cflags=CFLAGS
Use additional compiler flags CFLAGS to build the parts of the
library which are always statically linked into applications and
libraries even with shared linking (that is, the object files
contained in lib*_nonshared.a libraries). The build process will
automatically use the appropriate flags, but this option can be
used to set additional flags required for building applications and
libraries, to match local policy. For example, if such a policy
requires that all code linked into applications must be built with
source fortification,
--with-nonshared-cflags=-Wp,-D_FORTIFY_SOURCE=2 will make sure
that the objects in libc_nonshared.a are compiled with this flag
(although this will not affect the generated code in this
particular case and potentially change debugging information and
metadata only).
--with-rtld-early-cflags=CFLAGS
Use additional compiler flags CFLAGS to build the early startup
code of the dynamic linker. These flags can be used to enable
early dynamic linker diagnostics to run on CPUs which are not
compatible with the rest of the GNU C Library, for example, due to
compiler flags which target a later instruction set architecture
(ISA).
--with-timeoutfactor=NUM
Specify an integer NUM to scale the timeout of test programs. This
factor can be changed at run time using TIMEOUTFACTOR environment
variable.
--disable-shared
Dont build shared libraries even if it is possible. Not all
systems support shared libraries; you need ELF support and
(currently) the GNU linker.
--disable-default-pie
Dont build glibc programs and the testsuite as position
independent executables (PIE). By default, glibc programs and tests
are created as position independent executables on targets that
support it. If the toolchain and architecture support it, static
executables are built as static PIE and the resulting glibc can be
used with the GCC option, -static-pie, which is available with GCC
8 or above, to create static PIE.
--enable-cet
--enable-cet=permissive
Enable Intel Control-flow Enforcement Technology (CET) support.
When the GNU C Library is built with --enable-cet or
--enable-cet=permissive, the resulting library is protected with
indirect branch tracking (IBT) and shadow stack (SHSTK). When CET
is enabled, the GNU C Library is compatible with all existing
executables and shared libraries. This feature is currently
supported on x86_64 and x32 with GCC 8 and binutils 2.29 or later.
With --enable-cet, it is an error to dlopen a non CET enabled
shared library in CET enabled application. With
--enable-cet=permissive, CET is disabled when dlopening a non CET
enabled shared library in CET enabled application.
NOTE: --enable-cet is only supported on x86_64 and x32.
--enable-memory-tagging
Enable memory tagging support if the architecture supports it.
When the GNU C Library is built with this option then the resulting
library will be able to control the use of tagged memory when
hardware support is present by use of the tunable
glibc.mem.tagging. This includes the generation of tagged memory
when using the malloc APIs.
At present only AArch64 platforms with MTE provide this
functionality, although the library will still operate (without
memory tagging) on older versions of the architecture.
The default is to disable support for memory tagging.
--disable-profile
Dont build libraries with profiling information. You may want to
use this option if you dont plan to do profiling.
--enable-static-nss
Compile static versions of the NSS (Name Service Switch) libraries.
This is not recommended because it defeats the purpose of NSS; a
program linked statically with the NSS libraries cannot be
dynamically reconfigured to use a different name database.
--enable-hardcoded-path-in-tests
By default, dynamic tests are linked to run with the installed C
library. This option hardcodes the newly built C library path in
dynamic tests so that they can be invoked directly.
--disable-timezone-tools
By default, timezone related utilities (zic, zdump, and
tzselect) are installed with the GNU C Library. If you are
building these independently (e.g. by using the tzcode package),
then this option will allow disabling the install of these.
Note that you need to make sure the external tools are kept in sync
with the versions that the GNU C Library expects as the data
formats may change over time. Consult the timezone subdirectory
for more details.
--enable-stack-protector
--enable-stack-protector=strong
--enable-stack-protector=all
Compile the C library and all other parts of the glibc package
(including the threading and math libraries, NSS modules, and
transliteration modules) using the GCC -fstack-protector,
-fstack-protector-strong or -fstack-protector-all options to
detect stack overruns. Only the dynamic linker and a small number
of routines called directly from assembler are excluded from this
protection.
--enable-bind-now
Disable lazy binding for installed shared objects and programs.
This provides additional security hardening because it enables full
RELRO and a read-only global offset table (GOT), at the cost of
slightly increased program load times.
--enable-pt_chown
The file pt_chown is a helper binary for grantpt (*note
Pseudo-Terminals: Allocation.) that is installed setuid root to fix
up pseudo-terminal ownership on GNU/Hurd. It is not required on
GNU/Linux, and the GNU C Library will not use the installed
pt_chown program when configured with --enable-pt_chown.
--disable-werror
By default, the GNU C Library is built with -Werror. If you wish
to build without this option (for example, if building with a newer
version of GCC than this version of the GNU C Library was tested
with, so new warnings cause the build with -Werror to fail), you
can configure with --disable-werror.
--disable-mathvec
By default for x86_64, the GNU C Library is built with the vector
math library. Use this option to disable the vector math library.
--disable-scv
Disable using scv instruction for syscalls. All syscalls will
use sc instead, even if the kernel supports scv. PowerPC only.
--build=BUILD-SYSTEM
--host=HOST-SYSTEM
These options are for cross-compiling. If you specify both options
and BUILD-SYSTEM is different from HOST-SYSTEM, configure will
prepare to cross-compile the GNU C Library from BUILD-SYSTEM to be
used on HOST-SYSTEM. Youll probably need the --with-headers
option too, and you may have to override CONFIGUREs selection of
the compiler and/or binutils.
If you only specify --host, configure will prepare for a native
compile but use what you specify instead of guessing what your
system is. This is most useful to change the CPU submodel. For
example, if configure guesses your machine as i686-pc-linux-gnu
but you want to compile a library for 586es, give
--host=i586-pc-linux-gnu or just --host=i586-linux and add the
appropriate compiler flags (-mcpu=i586 will do the trick) to
CC.
If you specify just --build, configure will get confused.
--with-pkgversion=VERSION
Specify a description, possibly including a build number or build
date, of the binaries being built, to be included in --version
output from programs installed with the GNU C Library. For
example, --with-pkgversion='FooBar GNU/Linux glibc build 123'.
The default value is GNU libc.
--with-bugurl=URL
Specify the URL that users should visit if they wish to report a
bug, to be included in --help output from programs installed with
the GNU C Library. The default value refers to the main
bug-reporting information for the GNU C Library.
--enable-fortify-source
--enable-fortify-source=LEVEL
Use -D_FORTIFY_SOURCE=LEVEL to control hardening in the GNU C
Library. If not provided, LEVEL defaults to highest possible
value supported by the build compiler.
Default is to disable fortification.
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 arent. Look for error messages from make containing ***.
Those indicate that something is seriously wrong.
The compilation process can take a long time, depending on the
configuration and the speed of your machine. Some complex modules may
take a very long time to compile, as much as several minutes on slower
machines. Do not panic if the compiler appears to hang.
If you want to run a parallel make, simply pass the -j option with
an appropriate numeric parameter to make. You need a recent GNU
make version, though.
To build and run test programs which exercise some of the library
facilities, type make check. If it does not complete successfully, do
not use the built library, and report a bug after verifying that the
problem is not already known. *Note Reporting Bugs::, for instructions
on reporting bugs. Note that some of the tests assume they are not
being run by root. We recommend you compile and test the GNU C
Library as an unprivileged user.
Before reporting bugs make sure there is no problem with your system.
The tests (and later installation) use some pre-existing files of the
system such as /etc/passwd, /etc/nsswitch.conf and others. These
files must all contain correct and sensible content.
Normally, make check will run all the tests before reporting all
problems found and exiting with error status if any problems occurred.
You can specify stop-on-test-failure=y when running make check to
make the test run stop and exit with an error status immediately when a
failure occurs.
To format the GNU C Library Reference Manual for printing, type
make dvi. You need a working TeX installation to do this. The
distribution builds the on-line formatted version of the manual, as Info
files, as part of the build process. You can build them manually with
make info.
The library has a number of special-purpose configuration parameters
which you can find in Makeconfig. These can be overwritten with the
file configparms. To change them, create a configparms in your
build directory and add values as appropriate for your system. The file
is included and parsed by make and has to follow the conventions for
makefiles.
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: configure TARGET CC=TARGET-gcc. Set BUILD_CC to the compiler
to use for programs run on the build system as part of compiling the
library. You may need to set AR to cross-compiling versions of ar
if the native tools are not configured to work with object files for the
target you configured for. When cross-compiling the GNU C Library, it
may be tested using make check
test-wrapper="SRCDIR/scripts/cross-test-ssh.sh HOSTNAME", where SRCDIR
is the absolute directory name for the main source directory and
HOSTNAME is the host name of a system that can run the newly built
binaries of the GNU C Library. The source and build directories must be
visible at the same locations on both the build system and HOSTNAME.
The cross-test-ssh.sh script requires flock from util-linux to
work when GLIBC_TEST_ALLOW_TIME_SETTING environment variable is set.
It is also possible to execute tests, which require setting the date
on the target machine. Following use cases are supported:
GLIBC_TEST_ALLOW_TIME_SETTING is set in the environment in which
eligible tests are executed and have the privilege to run
clock_settime. In this case, nothing prevents those tests from
running in parallel, so the caller shall assure that those tests
are serialized or provide a proper wrapper script for them.
• The cross-test-ssh.sh script is used and one passes the
--allow-time-setting flag. In this case, both sets
GLIBC_TEST_ALLOW_TIME_SETTING and serialization of test execution
are assured automatically.
In general, when testing the GNU C Library, test-wrapper may be set
to the name and arguments of any program to run newly built binaries.
This program must preserve the arguments to the binary being run, its
working directory and the standard input, output and error file
descriptors. If TEST-WRAPPER env will not work to run a program with
environment variables set, then test-wrapper-env must be set to a
program that runs a newly built program with environment variable
assignments in effect, those assignments being specified as VAR=VALUE
before the name of the program to be run. If multiple assignments to
the same variable are specified, the last assignment specified must take
precedence. Similarly, if TEST-WRAPPER env -i will not work to run a
program with an environment completely empty of variables except those
directly assigned, then test-wrapper-env-only must be set; its use has
the same syntax as test-wrapper-env, the only difference in its
semantics being starting with an empty set of environment variables
rather than the ambient set.
For AArch64 with SVE, when testing the GNU C Library, test-wrapper
may be set to "SRCDIR/sysdeps/unix/sysv/linux/aarch64/vltest.py
VECTOR-LENGTH" to change Vector Length.
Installing the C Library
========================
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; however, you should still compile everything
first. If you are installing the GNU C Library as your primary C
library, we recommend that you shut the system down to single-user mode
first, and reboot afterward. This minimizes the risk of breaking things
when the library changes out from underneath.
make install will do the entire job of upgrading from a previous
installation of the GNU C Library version 2.x. There may sometimes be
headers left behind from the previous installation, but those are
generally harmless. If you want to avoid leaving headers behind you can
do things in the following order.
You must first build the library (make), optionally check it (make
check), switch the include directories and then install (make
install). The steps must be done in this order. Not moving the
directory before install will result in an unusable mixture of header
files from both libraries, but configuring, building, and checking the
library requires the ability to compile and run programs against the old
library. The new /usr/include, after switching the include
directories and before installing the library should contain the Linux
headers, but nothing else. If you do this, you will need to restore any
headers from libraries other than the GNU C Library yourself after
installing the library.
You can install the GNU C Library somewhere other than where you
configured it to go by setting the DESTDIR GNU standard make variable
on the command line for make install. The value of this variable is
prepended to all the paths for installation. This is useful when
setting up a chroot environment or preparing a binary distribution. The
directory should be specified with an absolute file name. Installing
with the prefix and exec_prefix GNU standard make variables set is
not supported.
The GNU C Library includes a daemon called nscd, which you may or
may not want to run. nscd caches name service lookups; it can
dramatically improve performance with NIS+, and may help with DNS as
well.
One auxiliary program, /usr/libexec/pt_chown, is installed setuid
root if the --enable-pt_chown configuration option is used. This
program is invoked by the grantpt function; it sets the permissions on
a pseudoterminal so it can be used by the calling process. If you are
using a Linux kernel with the devpts filesystem enabled and mounted at
/dev/pts, you dont need this program.
After installation you should configure the timezone and install
locales for your system. The time zone configuration ensures that your
system time matches the time for your current timezone. The locales
ensure that the display of information on your system matches the
expectations of your language and geographic region.
The GNU C Library is able to use two kinds of localization
information sources, the first is a locale database named
locale-archive which is generally installed as
/usr/lib/locale/locale-archive. The locale archive has the benefit of
taking up less space and being very fast to load, but only if you plan
to install sixty or more locales. If you plan to install one or two
locales you can instead install individual locales into their self-named
directories e.g. /usr/lib/locale/en_US.utf8. For example to install
the German locale using the character set for UTF-8 with name de_DE
into the locale archive issue the command localedef -i de_DE -f UTF-8
de_DE, and to install just the one locale issue the command localedef
--no-archive -i de_DE -f UTF-8 de_DE. To configure all locales that
are supported by the GNU C Library, you can issue from your build
directory the command make localedata/install-locales to install all
locales into the locale archive or make
localedata/install-locale-files to install all locales as files in the
default configured locale installation directory (derived from
--prefix or --localedir). To install into an alternative system
root use DESTDIR e.g. make localedata/install-locale-files
DESTDIR=/opt/glibc, but note that this does not change the configured
prefix.
To configure the locally used timezone, set the TZ environment
variable. The script tzselect helps you to select the right value.
As an example, for Germany, tzselect would tell you to use
TZ='Europe/Berlin'. For a system wide installation (the given paths
are for an installation with --prefix=/usr), link the timezone file
which is in /usr/share/zoneinfo to the file /etc/localtime. For
Germany, you might execute ln -s /usr/share/zoneinfo/Europe/Berlin
/etc/localtime.
Recommended Tools for Compilation
=================================
We recommend installing the following GNU tools before attempting to
build the GNU C Library:
• GNU make 4.0 or newer
As of release time, GNU make 4.4.1 is the newest verified to work
to build the GNU C Library.
• GCC 6.2 or newer
GCC 6.2 or higher is required. In general it is recommended to use
the newest version of the compiler that is known to work for
building the GNU C Library, as newer compilers usually produce
better code. As of release time, GCC 13.2 is the newest compiler
verified to work to build the GNU C Library.
For PowerPC 64-bits little-endian (powerpc64le), a GCC version with
support for -mno-gnu-attribute, -mabi=ieeelongdouble, and
-mabi=ibmlondouble is required. Likewise, the compiler must also
support passing -mlong-double-128 with the preceding options. As
of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0,
see GCC PR94200). These additional features are required for
building the GNU C Library with support for IEEE long double.
For ARC architecture builds, GCC 8.3 or higher is needed.
For s390x architecture builds, GCC 7.1 or higher is needed (See gcc
Bug 98269).
For AArch64 architecture builds with mathvec enabled, GCC 10 or
higher is needed due to dependency on arm_sve.h.
For multi-arch support it is recommended to use a GCC which has
been built with support for GNU indirect functions. This ensures
that correct debugging information is generated for functions
selected by IFUNC resolvers. This support can either be enabled by
configuring GCC with --enable-gnu-indirect-function, or by
enabling it by default by setting default_gnu_indirect_function
variable for a particular architecture in the GCC source file
gcc/config.gcc.
You can use whatever compiler you like to compile programs that use
the GNU C Library.
Check the FAQ for any special compiler issues on particular
platforms.
• GNU binutils 2.25 or later
You must use GNU binutils (as and ld) to build the GNU C Library.
No other assembler or linker has the necessary functionality at the
moment. As of release time, GNU binutils 2.42 is the newest
verified to work to build the GNU C Library.
For PowerPC 64-bits little-endian (powerpc64le), objcopy is
required to support --update-section. This option requires
binutils 2.26 or newer.
ARC architecture needs binutils 2.32 or higher for TLS related
fixes.
• GNU texinfo 4.7 or later
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 mechanism for the info files is not present or works
differently. As of release time, texinfo 7.0.3 is the newest
verified to work to build the GNU C Library.
• GNU awk 3.1.2, or higher
awk is used in several places to generate files. Some gawk
extensions are used, including the asorti function, which was
introduced in version 3.1.2 of gawk. As of release time, gawk
version 5.2.2 is the newest verified to work to build the GNU C
Library.
• GNU bison 2.7 or later
bison is used to generate the yacc parser code in the intl
subdirectory. As of release time, bison version 3.8.2 is the
newest verified to work to build the GNU C Library.
• Perl 5
Perl is not required, but if present it is used in some tests and
the mtrace program, to build the GNU C Library manual. As of
release time perl version 5.38.2 is the newest verified to work
to build the GNU C Library.
• GNU sed 3.02 or newer
Sed is used in several places to generate files. Most scripts
work with any version of sed. As of release time, sed version
4.9 is the newest verified to work to build the GNU C Library.
• Python 3.4 or later
Python is required to build the GNU C Library. As of release time,
Python 3.11 is the newest verified to work for building and testing
the GNU C Library.
• PExpect 4.0
The pretty printer tests drive GDB through test programs and
compare its output to the printers. PExpect is used to capture
the output of GDB, and should be compatible with the Python version
in your system. As of release time PExpect 4.8.0 is the newest
verified to work to test the pretty printers.
• The Python abnf module.
This module is optional and used to verify some ABNF grammars in
the manual. Version 2.2.0 has been confirmed to work as expected.
A missing abnf module does not reduce the test coverage of the
library itself.
• GDB 7.8 or later with support for Python 2.7/3.4 or later
GDB itself needs to be configured with Python support in order to
use the pretty printers. Notice that your system having Python
available doesnt imply that GDB supports it, nor that your
systems Python and GDBs have the same version. As of release
time GNU debugger 13.2 is the newest verified to work to test the
pretty printers.
Unless Python, PExpect and GDB with Python support are present, the
printer tests will report themselves as UNSUPPORTED. Notice that
some of the printer tests require the GNU C Library to be compiled
with debugging symbols.
If you change any of the configure.ac files you will also need
• GNU autoconf 2.71 (exactly)
and if you change any of the message translation files you will need
• GNU gettext 0.10.36 or later
As of release time, GNU gettext version 0.21.1 is the newest
version verified to work to build the GNU C Library.
You may also need these packages if you upgrade your source tree using
patches, although we try to avoid this.
Specific advice for GNU/Linux systems
=====================================
If you are installing the GNU C Library on GNU/Linux systems, you need
to have the header files from a 3.2 or newer kernel around for
reference. These headers must be installed using make
headers_install; the headers present in the kernel source directory are
not suitable for direct use by the GNU C Library. You do not need to
use that kernel, just have its headers installed where the GNU C Library
can access them, referred to here as INSTALL-DIRECTORY. The easiest way
to do this is to unpack it in a directory such as
/usr/src/linux-VERSION. In that directory, run make headers_install
INSTALL_HDR_PATH=INSTALL-DIRECTORY. Finally, configure the GNU C
Library with the option --with-headers=INSTALL-DIRECTORY/include. Use
the most recent kernel you can get your hands on. (If you are
cross-compiling the GNU C Library, you need to specify
ARCH=ARCHITECTURE in the make headers_install command, where
ARCHITECTURE is the architecture name used by the Linux kernel, such as
x86 or powerpc.)
After installing the GNU C Library, you may need to remove or rename
directories such as /usr/include/linux and /usr/include/asm, and
replace them with copies of directories such as linux and asm from
INSTALL-DIRECTORY/include. All directories present in
INSTALL-DIRECTORY/include should be copied, except that the GNU C
Library provides its own version of /usr/include/scsi; the files
provided by the kernel should be copied without replacing those provided
by the GNU C Library. The linux, asm and asm-generic directories
are required to compile programs using the GNU C Library; the other
directories describe interfaces to the kernel but are not required if
not compiling programs using those interfaces. You do not need to copy
kernel headers if you did not specify an alternate kernel header source
using --with-headers.
The Filesystem Hierarchy Standard for GNU/Linux systems expects some
components of the GNU C Library installation to be in /lib and some in
/usr/lib. This is handled automatically if you configure the GNU C
Library with --prefix=/usr. If you set some other prefix or allow it
to default to /usr/local, then all the components are installed there.
As of release time, Linux version 6.1.5 is the newest stable version
verified to work to build the GNU C Library.
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 dont, no one will ever know about them and they will
remain unfixed for all eternity, if not longer.
It is a good idea to verify that the problem has not already been
reported. Bugs are documented in two places: The file BUGS describes
a number of well known bugs and the central GNU C Library bug tracking
system has a WWW interface at <https://sourceware.org/bugzilla/>. The
WWW interface gives you access to open and closed reports. A closed
report normally includes a patch or a hint on solving the problem.
To report a bug, first you must find it. With any luck, this will be
the hard part. Once youve found a bug, make sure its 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. It might not be the GNU C Library. Many historical
Unix C libraries permit things that we dont, such as closing a file
twice.
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!
Once youre sure youve 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.
Do this at <https://www.gnu.org/software/libc/bugs.html>.
If you are not sure how a function should behave, and this manual
doesnt tell you, thats a bug in the manual. Report that too! If the
functions 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 bug
database. If you refer to specific sections of the manual, please
include the section names for easier identification.