@include macros.texi

@include pkgvers.texi

@ifclear plain

@node Installation, Maintenance, Library Summary, Top

@end ifclear

@c %MENU% How to install the GNU C Library

@appendix Installing @theglibc{}

Before you do anything else, you should read the FAQ at

@url{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.  @xref{Tools for Compilation}, below.

@ifclear plain

@menu

* Configuring and compiling::   How to compile and test GNU libc.

* Running make install::        How to install it once you've got it

 compiled.

* Tools for Compilation::       You'll need these first.

* Linux::                       Specific advice for GNU/Linux systems.

* Reporting Bugs::              So they'll get fixed.

@end menu

@end ifclear

@node Configuring and compiling

@appendixsec Configuring and compiling @theglibc{}

@cindex configuring

@cindex compiling

@Theglibc{} cannot be compiled in the source directory.  You must build

it in a separate build directory.  For example, if you have unpacked

the @glibcadj{} sources in @file{/src/gnu/glibc-@var{version}},

create a directory

@file{/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 @file{configure} located

at the top level of the source tree.  In the scenario above, you'd type

@smallexample

$ ../glibc-@var{version}/configure @var{args@dots{}}

@end smallexample

Please note that even though you're building in a separate build

directory, the compilation may need to create or modify files and

directories in the source directory.

@noindent

@code{configure} takes many options, but the only one that is usually

mandatory is @samp{--prefix}.  This option tells @code{configure}

where you want @theglibc{} installed.  This defaults to @file{/usr/local},

but the normal setting to install as the standard system library is

@samp{--prefix=/usr} for @gnulinuxsystems{} and @samp{--prefix=} (an

empty prefix) for @gnuhurdsystems{}.

It may also be useful to pass @samp{CC=@var{compiler}} and

@code{CFLAGS=@var{flags}} arguments to @code{configure}.  @code{CC}

selects the C compiler that will be used, and @code{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 @code{CC}.  Options

that may be overridden by the @glibcadj{} build system for particular

files, such as for optimization and debugging, should go in

@code{CFLAGS}.  The default value of @code{CFLAGS} is @samp{-g -O2},

and @theglibc{} cannot be compiled without optimization, so if

@code{CFLAGS} is specified it must enable optimization.  For example:

@smallexample

$ ../glibc-@var{version}/configure CC="gcc -m32" CFLAGS="-O3"

@end smallexample

The following list describes all of the available options for

 @code{configure}:

@table @samp

@item --prefix=@var{directory}

Install machine-independent data files in subdirectories of

@file{@var{directory}}.  The default is to install in @file{/usr/local}.

@item --exec-prefix=@var{directory}

Install the library and other machine-dependent files in subdirectories

of @file{@var{directory}}.  The default is to the @samp{--prefix}

directory if that option is specified, or @file{/usr/local} otherwise.

@item --with-headers=@var{directory}

Look for kernel header files in @var{directory}, not

@file{/usr/include}.  @Theglibc{} needs information from the kernel's header

files describing the interface to the kernel.  @Theglibc{} will normally

look in @file{/usr/include} for them,

but if you specify this option, it will look in @var{DIRECTORY} instead.

This option is primarily of use on a system where the headers in

@file{/usr/include} come from an older version of @theglibc{}.  Conflicts can

occasionally happen in this case.  You can also use this option if you want to

compile @theglibc{} with a newer set of kernel headers than the ones found in

@file{/usr/include}.

@item --enable-kernel=@var{version}

This option is currently only useful on @gnulinuxsystems{}.  The

@var{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 @var{version} number is, the less

compatibility code is added, and the faster the code gets.

@item --with-binutils=@var{directory}

Use the binutils (assembler and linker) in @file{@var{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 @theglibc{}.  In that case, @code{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 can't build a

shared libc with old binutils.

@item --with-nonshared-cflags=@var{cflags}

Use additional compiler flags @var{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 @file{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.

@c disable static doesn't work currently

@c @item --disable-static

@c Don't build static libraries.  Static libraries aren't that useful these

@c days, but we recommend you build them in case you need them.

@item --disable-shared

Don't build shared libraries even if it is possible.  Not all systems

support shared libraries; you need ELF support and (currently) the GNU

linker.

@item --enable-static-pie

Enable static position independent executable (static PIE) support.

Static PIE is similar to static executable, but can be loaded at any

address without help from a dynamic linker.  All static programs as

well as static tests are built as static PIE, except for those marked

with no-pie.  The resulting glibc can be used with the GCC option,

-static-pie, which is available with GCC 8 or above, to create static

PIE.  This option also implies that glibc programs and tests are created

as dynamic position independent executables (PIE) by default.

@item --enable-cet

@itemx --enable-cet=permissive

Enable Intel Control-flow Enforcement Technology (CET) support.  When

@theglibc{} is built with @option{--enable-cet} or

@option{--enable-cet=permissive}, the resulting library

is protected with indirect branch tracking (IBT) and shadow stack

(SHSTK)@.  When CET is enabled, @theglibc{} is compatible with all

existing executables and shared libraries.  This feature is currently

supported on i386, x86_64 and x32 with GCC 8 and binutils 2.29 or later.

Note that when CET is enabled, @theglibc{} requires CPUs capable of

multi-byte NOPs, like x86-64 processors as well as Intel Pentium Pro or

newer.  With @option{--enable-cet}, it is an error to dlopen a non CET

enabled shared library in CET enabled application.  With

@option{--enable-cet=permissive}, CET is disabled when dlopening a

non CET enabled shared library in CET enabled application.

NOTE: @option{--enable-cet} has been tested for i686, x86_64 and x32

on non-CET processors.  @option{--enable-cet} has been tested for

i686, x86_64 and x32 on CET processors.

@item --disable-profile

Don't build libraries with profiling information.  You may want to use

this option if you don't plan to do profiling.

@item --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.

@item --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.

@item --disable-timezone-tools

By default, timezone related utilities (@command{zic}, @command{zdump},

and @command{tzselect}) are installed with @theglibc{}.  If you are building

these independently (e.g. by using the @samp{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 @theglibc{} expects as the data formats may change over

time.  Consult the @file{timezone} subdirectory for more details.

@item --enable-stack-protector

@itemx --enable-stack-protector=strong

@itemx --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 @option{-fstack-protector},

@option{-fstack-protector-strong} or @option{-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.

@item --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.

@pindex pt_chown

@findex grantpt

@item --enable-pt_chown

The file @file{pt_chown} is a helper binary for @code{grantpt}

(@pxref{Allocation, Pseudo-Terminals}) that is installed setuid root to

fix up pseudo-terminal ownership.  It is not built by default because

systems using the Linux kernel are commonly built with the @code{devpts}

filesystem enabled and mounted at @file{/dev/pts}, which manages

pseudo-terminal ownership automatically.  By using

@samp{--enable-pt_chown}, you may build @file{pt_chown} and install it

setuid and owned by @code{root}.  The use of @file{pt_chown} introduces

additional security risks to the system and you should enable it only if

you understand and accept those risks.

@item --disable-werror

By default, @theglibc{} is built with @option{-Werror}.  If you wish

to build without this option (for example, if building with a newer

version of GCC than this version of @theglibc{} was tested with, so

new warnings cause the build with @option{-Werror} to fail), you can

configure with @option{--disable-werror}.

@item --disable-mathvec

By default for x86_64, @theglibc{} is built with the vector math library.

Use this option to disable the vector math library.

@item --enable-tunables

Tunables support allows additional library parameters to be customized at

runtime.  This feature is enabled by default.  This option can take the

following values:

@table @code

@item yes

This is the default if no option is passed to configure. This enables tunables

and selects the default frontend (currently @samp{valstring}).

@item no

This option disables tunables.

@item valstring

This enables tunables and selects the @samp{valstring} frontend for tunables.

This frontend allows users to specify tunables as a colon-separated list in a

single environment variable @env{GLIBC_TUNABLES}.

@end table

@item --enable-obsolete-nsl

By default, libnsl is only built as shared library for backward

compatibility and the NSS modules libnss_compat, libnss_nis and

libnss_nisplus are not built at all.

Use this option to enable libnsl with all depending NSS modules and

header files.

@item --disable-crypt

Do not install the passphrase-hashing library @file{libcrypt} or the

header file @file{crypt.h}.  @file{unistd.h} will still declare the

function @code{crypt}.  Using this option does not change the set of

programs that may need to be linked with @option{-lcrypt}; it only

means that @theglibc{} will not provide that library.

This option is for hackers and distributions experimenting with

independently-maintained implementations of libcrypt.  It may become

the default in a future release.

@item --disable-experimental-malloc

By default, a per-thread cache is enabled in @code{malloc}.  While

this cache can be disabled on a per-application basis using tunables

(set glibc.malloc.tcache_count to zero), this option can be used to

remove it from the build completely.

@item --build=@var{build-system}

@itemx --host=@var{host-system}

These options are for cross-compiling.  If you specify both options and

@var{build-system} is different from @var{host-system}, @code{configure}

will prepare to cross-compile @theglibc{} from @var{build-system} to be used

on @var{host-system}.  You'll probably need the @samp{--with-headers}

option too, and you may have to override @var{configure}'s selection of

the compiler and/or binutils.

If you only specify @samp{--host}, @code{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 @code{configure} guesses your machine as @code{i686-pc-linux-gnu} but

you want to compile a library for 586es, give

@samp{--host=i586-pc-linux-gnu} or just @samp{--host=i586-linux} and add

the appropriate compiler flags (@samp{-mcpu=i586} will do the trick) to

@code{CC}.

If you specify just @samp{--build}, @code{configure} will get confused.

@item --with-pkgversion=@var{version}

Specify a description, possibly including a build number or build

date, of the binaries being built, to be included in

@option{--version} output from programs installed with @theglibc{}.

For example, @option{--with-pkgversion='FooBar GNU/Linux glibc build

123'}.  The default value is @samp{GNU libc}.

@item --with-bugurl=@var{url}

Specify the URL that users should visit if they wish to report a bug,

to be included in @option{--help} output from programs installed with

@theglibc{}.  The default value refers to the main bug-reporting

information for @theglibc{}.

@end table

To build the library and related programs, type @code{make}.  This will

produce a lot of output, some of which may look like errors from

@code{make} but aren't.  Look for error messages from @code{make}

containing @samp{***}.  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 @samp{-j} option

with an appropriate numeric parameter to @code{make}.  You need a recent

GNU @code{make} version, though.

To build and run test programs which exercise some of the library

facilities, type @code{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.  @xref{Reporting Bugs},

for instructions on reporting bugs.  Note that some of the tests assume

they are not being run by @code{root}.  We recommend you compile and

test @theglibc{} 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 @file{/etc/passwd}, @file{/etc/nsswitch.conf} and others.

These files must all contain correct and sensible content.

Normally, @code{make check} will run all the tests before reporting

all problems found and exiting with error status if any problems

occurred.  You can specify @samp{stop-on-test-failure=y} when running

@code{make check} to make the test run stop and exit with an error

status immediately when a failure occurs.

The @glibcadj{} pretty printers come with their own set of scripts for testing,

which run together with the rest of the testsuite through @code{make check}.

These scripts require the following tools to run successfully:

@itemize @bullet

@item

Python 2.7/3.4 or later

Python is required for running the printers' test scripts. As of release time,

Python 3.6 is the newest verified to work to test the pretty printers.

@item PExpect 4.0

The 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 4.3 is the newest verified to work to test the pretty printers.

@item

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 doesn't imply

that GDB supports it, nor that your system's Python and GDB's have the same

version. As of release time GNU @code{debugger} 8.0.1 is the newest verified

to work to test the pretty printers.

@end itemize

@noindent

If these tools are absent, the printer tests will report themselves as

@code{UNSUPPORTED}.  Notice that some of the printer tests require @theglibc{}

to be compiled with debugging symbols.

To format the @cite{GNU C Library Reference Manual} for printing, type

@w{@code{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 @w{@code{make info}}.

The library has a number of special-purpose configuration parameters

which you can find in @file{Makeconfig}.  These can be overwritten with

the file @file{configparms}.  To change them, create a

@file{configparms} in your build directory and add values as appropriate

for your system.  The file is included and parsed by @code{make} and has

to follow the conventions for makefiles.

It is easy to configure @theglibc{} for cross-compilation by

setting a few variables in @file{configparms}.  Set @code{CC} to the

cross-compiler for the target you configured the library for; it is

important to use this same @code{CC} value when running

@code{configure}, like this: @samp{configure @var{target}

CC=@var{target}-gcc}.  Set @code{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 @code{AR} to cross-compiling versions of @code{ar}

if the native tools are not configured to work with

object files for the target you configured for.  When cross-compiling

@theglibc{}, it may be tested using @samp{make check

test-wrapper="@var{srcdir}/scripts/cross-test-ssh.sh @var{hostname}"},

where @var{srcdir} is the absolute directory name for the main source

directory and @var{hostname} is the host name of a system that can run

the newly built binaries of @theglibc{}.  The source and build

directories must be visible at the same locations on both the build

system and @var{hostname}.

In general, when testing @theglibc{}, @samp{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 @samp{@var{test-wrapper} env} will not work to run a

program with environment variables set, then @samp{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 @samp{@var{var}=@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 @samp{@var{test-wrapper} env -i} will not work to run a

program with an environment completely empty of variables except those

directly assigned, then @samp{test-wrapper-env-only} must be set; its

use has the same syntax as @samp{test-wrapper-env}, the only

difference in its semantics being starting with an empty set of

environment variables rather than the ambient set.

@node Running make install

@appendixsec Installing the C Library

@cindex installing

To install the library and its header files, and the Info files of the

manual, type @code{make install}.  This will

build things, if necessary, before installing them; however, you should

still compile everything first.  If you are installing @theglibc{} 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.

@samp{make install} will do the entire job of upgrading from a

previous installation of @theglibc{} 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 (@samp{make}), optionally check it

(@samp{make check}), switch the include directories and then install

(@samp{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 @file{/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 @theglibc{} yourself after installing the

library.

You can install @theglibc{} somewhere other than where you configured

it to go by setting the @code{DESTDIR} GNU standard make variable on

the command line for @samp{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 @code{prefix} and @code{exec_prefix} GNU standard make variables

set is not supported.

@Theglibc{} includes a daemon called @code{nscd}, which you

may or may not want to run.  @code{nscd} caches name service lookups; it

can dramatically improve performance with NIS+, and may help with DNS as

well.

One auxiliary program, @file{/usr/libexec/pt_chown}, is installed setuid

@code{root} if the @samp{--enable-pt_chown} configuration option is used.

This program is invoked by the @code{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 @code{devpts} filesystem enabled

and mounted at @file{/dev/pts}, you don't need this program.

After installation you might want to configure the timezone and locale

installation of your system.  @Theglibc{} comes with a locale

database which gets configured with @code{localedef}.  For example, to

set up a German locale with name @code{de_DE}, simply issue the command

@samp{localedef -i de_DE -f ISO-8859-1 de_DE}.  To configure all locales

that are supported by @theglibc{}, you can issue from your build directory the

command @samp{make localedata/install-locales}.

To configure the locally used timezone, set the @code{TZ} environment

variable.  The script @code{tzselect} helps you to select the right value.

As an example, for Germany, @code{tzselect} would tell you to use

@samp{TZ='Europe/Berlin'}.  For a system wide installation (the given

paths are for an installation with @samp{--prefix=/usr}), link the

timezone file which is in @file{/usr/share/zoneinfo} to the file

@file{/etc/localtime}.  For Germany, you might execute @samp{ln -s

/usr/share/zoneinfo/Europe/Berlin /etc/localtime}.

@node Tools for Compilation

@appendixsec Recommended Tools for Compilation

@cindex installation tools

@cindex tools, for installing library

We recommend installing the following GNU tools before attempting to

build @theglibc{}:

@itemize @bullet

@item

GNU @code{make} 4.0 or newer

As of relase time, GNU @code{make} 4.2.1 is the newest verified to work

to build @theglibc{}.

@item

GCC 4.9 or newer

GCC 4.9 or higher is required.  In general it is recommended to use

the newest version of the compiler that is known to work for building

@theglibc{}, as newer compilers usually produce better code.  As of

release time, GCC 8.1.1 is the newest compiler verified to work to build

@theglibc{}.

For PowerPC 64-bits little-endian (powerpc64le), GCC 6.2 or higher is

required.  This compiler version is the first to provide the features

required for building @theglibc{} with support for @code{_Float128}.

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

@samp{--enable-gnu-indirect-function}, or by enabling it by default by setting

@samp{default_gnu_indirect_function} variable for a particular architecture in

the GCC source file @file{gcc/config.gcc}.

You can use whatever compiler you like to compile programs that use

@theglibc{}.

Check the FAQ for any special compiler issues on particular platforms.

@item

GNU @code{binutils} 2.25 or later

You must use GNU @code{binutils} (as and ld) to build @theglibc{}.

No other assembler or linker has the necessary functionality at the

moment. As of release time, GNU @code{binutils} 2.31.1 is the newest

verified to work to build @theglibc{}.

@item

GNU @code{texinfo} 4.7 or later

To correctly translate and install the Texinfo documentation you need

this version of the @code{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, @code{texinfo} 6.5 is the newest verified to work

to build @theglibc{}.

@item

GNU @code{awk} 3.1.2, or higher

@code{awk} is used in several places to generate files.

Some @code{gawk} extensions are used, including the @code{asorti}

function, which was introduced in version 3.1.2 of @code{gawk}.

As of release time, @code{gawk} version 4.2.1 is the newest verified

to work to build @theglibc{}.

@item

GNU @code{bison} 2.7 or later

@code{bison} is used to generate the @code{yacc} parser code in the @file{intl}

subdirectory.  As of release time, @code{bison} version 3.0.4 is the newest

verified to work to build @theglibc{}.

@item

Perl 5

Perl is not required, but it is used if present to test the

installation.  We may decide to use it elsewhere in the future. As of release

time @code{perl} version 5.28.0 is the newest verified to work to build

@theglibc{}.

@item

GNU @code{sed} 3.02 or newer

@code{Sed} is used in several places to generate files.  Most scripts work

with any version of @code{sed}.  As of release time, @code{sed} version

4.5 is the newest verified to work to build @theglibc{}.

@end itemize

@noindent

If you change any of the @file{configure.ac} files you will also need

@itemize @bullet

@item

GNU @code{autoconf} 2.69 (exactly)

@end itemize

@noindent

and if you change any of the message translation files you will need

@itemize @bullet

@item

GNU @code{gettext} 0.10.36 or later

As of release time, GNU @code{gettext} version 0.19.8.1 is the newest

version verified to work to build @theglibc{}.

@end itemize

@noindent

You may also need these packages if you upgrade your source tree using

patches, although we try to avoid this.

@node Linux

@appendixsec Specific advice for @gnulinuxsystems{}

@cindex kernel header files

If you are installing @theglibc{} on @gnulinuxsystems{}, you need to have

the header files from a 3.2 or newer kernel around for reference.

(For the ia64 architecture, you need version 3.2.18 or newer because this

is the first version with support for the @code{accept4} system call.)

These headers must be installed using @samp{make headers_install}; the

headers present in the kernel source directory are not suitable for

direct use by @theglibc{}.  You do not need to use that kernel, just have

its headers installed where @theglibc{} can access them, referred to here as

@var{install-directory}.  The easiest way to do this is to unpack it

in a directory such as @file{/usr/src/linux-@var{version}}.  In that

directory, run @samp{make headers_install

INSTALL_HDR_PATH=@var{install-directory}}.  Finally, configure @theglibc{}

with the option @samp{--with-headers=@var{install-directory}/include}.

Use the most recent kernel you can get your hands on.  (If you are

cross-compiling @theglibc{}, you need to specify

@samp{ARCH=@var{architecture}} in the @samp{make headers_install}

command, where @var{architecture} is the architecture name used by the

Linux kernel, such as @samp{x86} or @samp{powerpc}.)

After installing @theglibc{}, you may need to remove or rename

directories such as @file{/usr/include/linux} and

@file{/usr/include/asm}, and replace them with copies of directories

such as @file{linux} and @file{asm} from

@file{@var{install-directory}/include}.  All directories present in

@file{@var{install-directory}/include} should be copied, except that

@theglibc{} provides its own version of @file{/usr/include/scsi}; the

files provided by the kernel should be copied without replacing those

provided by @theglibc{}.  The @file{linux}, @file{asm} and

@file{asm-generic} directories are required to compile programs using

@theglibc{}; 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 @samp{--with-headers}.

The Filesystem Hierarchy Standard for @gnulinuxsystems{} expects some

components of the @glibcadj{} installation to be in

@file{/lib} and some in @file{/usr/lib}.  This is handled automatically

if you configure @theglibc{} with @samp{--prefix=/usr}.  If you set some other

prefix or allow it to default to @file{/usr/local}, then all the

components are installed there.

@node Reporting Bugs

@appendixsec Reporting Bugs

@cindex reporting bugs

@cindex bugs, reporting

There are probably bugs in @theglibc{}.  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.

It is a good idea to verify that the problem has not already been

reported.  Bugs are documented in two places: The file @file{BUGS}

describes a number of well known bugs and the central @glibcadj{}

bug tracking system has a

WWW interface at

@url{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 you've found a bug, make sure it's really a bug.  A

good way to do this is to see if @theglibc{} 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 @theglibc{}.  Many historical

Unix C libraries permit things that we don't, such as closing a file

twice.

If you think you have found some way in which @theglibc{} does not

conform to the ISO and POSIX standards (@pxref{Standards and

Portability}), that is definitely a bug.  Report it!

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.

Do this at @value{REPORT_BUGS_TO}.

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

bug database.  If you refer to specific

sections of the manual, please include the section names for easier

identification.