library will still be usable, but functionality may be lost--for
example, you can't 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'
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.
-'--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.
+'--disable-default-pie'
+ Don't 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 i386, x86_64 and x32 with GCC 8 and binutils 2.29 or
+ later. Note that when CET is enabled, the GNU C Library requires
+ CPUs capable of multi-byte NOPs, like x86-64 processors as well as
+ Intel Pentium Pro or newer. 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' has been tested for i686, x86_64 and x32 on
+ non-CET processors. '--enable-cet' has been tested for i686,
+ x86_64 and x32 on CET processors.
+
+'--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'
Don't build libraries with profiling information. You may want to
protection.
'--enable-bind-now'
- Disable lazy binding for installed shared objects. 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.
+ 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. It is not built by default because
- systems using the Linux kernel are commonly built with the 'devpts'
- filesystem enabled and mounted at '/dev/pts', which manages
- pseudo-terminal ownership automatically. By using
- '--enable-pt_chown', you may build 'pt_chown' and install it setuid
- and owned by 'root'. The use of 'pt_chown' introduces additional
- security risks to the system and you should enable it only if you
- understand and accept those risks.
+ 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
colon-separated list in a single environment variable
'GLIBC_TUNABLES'.
-'--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.
-
'--disable-crypt'
Do not install the passphrase-hashing library 'libcrypt' or the
header file 'crypt.h'. 'unistd.h' will still declare the function
independently-maintained implementations of libcrypt. It may
become the default in a future release.
-'--disable-experimental-malloc'
- By default, a per-thread cache is enabled in '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.
+'--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'
make the test run stop and exit with an error status immediately when a
failure occurs.
- The GNU C Library pretty printers come with their own set of scripts
-for testing, which run together with the rest of the testsuite through
-'make check'. These scripts require the following tools to run
-successfully:
-
- * Python 2.7.6/3.4.3 or later
-
- Python is required for running the printers' test scripts.
-
- * 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.
-
- * GDB 7.8 or later with support for Python 2.7.6/3.4.3 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.
-
-If these tools are absent, 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.
-
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
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.
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
========================
using a Linux kernel with the 'devpts' filesystem enabled and mounted at
'/dev/pts', you don't need this program.
- After installation you might want to configure the timezone and
-locale installation of your system. The GNU C Library comes with a
-locale database which gets configured with 'localedef'. For example, to
-set up a German locale with name 'de_DE', simply issue the command
-'localedef -i de_DE -f ISO-8859-1 de_DE'. To configure all locales that
+ 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'.
+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.
* GNU 'make' 4.0 or newer
- * GCC 4.9 or newer
+ As of relase time, GNU 'make' 4.4 is the newest verified to work to
+ build the GNU C Library.
- GCC 4.9 or higher is required. In general it is recommended to use
+ * 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 7.3 is the newest compiler
+ better code. As of release time, GCC 13.0 is the newest compiler
verified to work to build the GNU C Library.
- 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 the GNU C Library with support for
- '_Float128'.
+ 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 multi-arch support it is recommended to use a GCC which has
been built with support for GNU indirect functions. This ensures
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' 2.29.1 is the newest
+ moment. As of release time, GNU 'binutils' 2.39 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' 6.5 is the newest
+ differently. As of release time, 'texinfo' 7.0.2 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 4.2.0 is the newest verified to work to build the GNU C
+ version 5.1.1 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 3.0.4 is the
+ 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 it is used if present to test the
- installation. We may decide to use it elsewhere in the future.
+ 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 5.36.0 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
- 4.4 is the newest verified to work to build the GNU C Library.
+ 4.8 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.
+
+ * 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 'debugger' 12.1 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 '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.
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
==============
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 <http://www.gnu.org/software/libc/bugs.html>.
+Do this at <https://www.gnu.org/software/libc/bugs.html>.
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
projects / thirdparty / glibc.git / blobdiff