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Reorganize and revise NEWS for 2.26.
This commit is contained in:
Zack Weinberg
parent
cc31b141f9
commit
2b2ccd0c63
289
NEWS
289
NEWS
@ -7,142 +7,64 @@ using `glibc' in the "product" field.
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Version 2.26
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Major new features:
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* Unicode 10.0.0 Support: Character encoding, character type info, and
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transliteration tables are all updated to Unicode 10.0.0, using
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generator scripts contributed by Mike FABIAN (Red Hat).
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* Collation of Hungarian has been overhauled and is now consistent with "The
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Rules of Hungarian Orthography, 12th edition" (Bug 18934). Contributed by
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Egmont Koblinger.
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* Improvements to the DNS stub resolver, contributed by Florian Weimer:
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- glibc will now detect when /etc/resolv.conf has been modified and reload
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the changed configuration. The new resolver option “no-reload”
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(RES_NORELOAD) disables this behavior.
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- glibc now supports an arbitrary number of search domains (configured using
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the “search” directive in /etc/resolv.conf); previously, there was a
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hard limit of six domains. For backward compatibility, applications
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that directly modify the ‘_res’ global object are still limited to six
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search domains.
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- When the “rotate” (RES_ROTATE) resolver option is active, glibc will now
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randomly pick a name server from the configuration as a starting point.
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(Previously, the second name server was always used.)
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* The tunables feature is now enabled by default. This allows users to tweak
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behavior of the GNU C Library using the GLIBC_TUNABLES environment variable.
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* New function reallocarray, which resizes an allocated block (like realloc)
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to the product of two sizes, with a guaranteed clean failure upon integer
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overflow in the multiplication. Originally from OpenBSD, contributed by
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Dennis Wölfing and Rüdiger Sonderfeld.
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* New wrappers for the Linux-specific system calls preadv2 and pwritev2.
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These are extended versions of preadv and pwritev, respectively, taking an
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additional flags argument. The set of supported flags depends on the
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running kernel; full support currently requires kernel 4.7 or later.
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* posix_spawnattr_setflags now supports the flag POSIX_SPAWN_SETSID, to
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create a new session ID for the spawned process. This feature is
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scheduled to be added to the next major revision of POSIX; for the time
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being, it is available under _GNU_SOURCE.
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* errno.h is now safe to use from C-preprocessed assembly language on all
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supported operating systems. In this context, it will only define the
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Exxxx constants, as preprocessor macros expanding to integer literals.
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* The rpcgen, librpcsvc and related headers will only be built and
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installed when glibc is configured with --enable-obsolete-rpc.
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This allows alternative RPC implementations, like TIRPC, to be used
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by default. Applications needing features missing from TIRPC should
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consider the rpcsvc-proto project developed by Thorsten Kukuk (SUSE).
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* On ia64, powerpc64le, x86-32, and x86-64, the math library now implements
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128-bit floating point as defined by IEEE 60559:2011 and ISO/IEC TS
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18661-3:2015. Support for more architectures will be added in future
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releases. Contributed by Paul E. Murphy, Gabriel F. T. Gomes, and Tulio
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Magno Quites Machado Filho.
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* The NIS(+) name service modules, libnss_nis, libnss_nisplus, and
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libnss_compat, are deprecated, and will not be built or installed by
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default. Replacement implementations based on TIRPC, which
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additionally support IPv6, are available from
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<https://github.com/thkukuk/libnss_{compat,nis,nisplus}>.
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* The NIS(+) support library, libnsl, is deprecated. By default, a
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compatibility shared library will be built and installed, but not
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headers or development libraries.
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Only a few NIS-related programs require this library.
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A replacement implementation based on TIRPC is available from
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<https://github.com/thkukuk/libnsl>. Like the replacement NIS(+)
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name service modules, the replacement supports IPv6, and it can be
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coinstalled with the compatibility shared library from glibc.
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* New configure option --enable-obsolete-nsl will cause libnsl's
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headers, and the NIS(+) name service modules, to be built and
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installed. This option may be removed in a future release.
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* Extensive new collation tests for Hungarian locales based on
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"The Rules of Hungarian Orthography, 12th edition" and the work of
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Egmont Koblinger (Bug 18934).
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* The DNS stub resolver no longer performs EDNS fallback. If EDNS or DNSSEC
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support is enabled, the configured recursive resolver must support EDNS.
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(Responding to EDNS-enabled queries with responses which are not
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EDNS-enabled is fine, but FORMERR responses are not.)
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* res_mkquery and res_nmkquery no longer support the IQUERY opcode. DNS
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servers have not supported this opcode for a long time.
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* The legacy cfree function has been removed. Applications should use the
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free function instead.
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* posix_spawnattr_setflags now supports POSIX_SPAWN_SETSID flag to create a
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new session ID for the posix_spawn and posix_spawnp. It is scheduled to
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be added on next major revision of POSIX, so current support is enabled
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with _GNU_SOURCE.
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* The minimum Linux kernel version that this version of the GNU C Library
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can be used with on i[4567]86 and x86_64 is 3.2. A Linux 3.2 or later
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kernel was already required on all other architectures.
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* The obsolete <sys/ultrasound.h> header file has been removed.
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* The port to Native Client running on ARMv7-A (--host=arm-nacl) has been
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removed.
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* <string.h> no longer includes inline versions of any string functions,
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as this kind of optimization is better done by the compiler. The macros
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__USE_STRING_INLINES and __NO_STRING_INLINES no longer have any effect.
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* The nonstandard header <xlocale.h> has been removed. Most programs should
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use <locale.h> instead. If you have a specific need for the definition
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of locale_t with no other declarations, please talk to us.
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* The obsolete signal constant SIGUNUSED is no longer defined by <signal.h>.
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* The reallocarray function has been added to libc. It is a realloc
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replacement with a check for integer overflow when calculating total
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allocation size.
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* New preadv2 and pwritev2 has been added. They are Linux extensions to
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preadv and pwritev with an additional flag argument where it is possible
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to set high priority or use O_DSYNC or O_SYNC for a specific IO operation.
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For complete support it requires Linux kernel version 4.6, otherwise a
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compat implementation will be used (which refuses all flags and routes it
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to preadv or pwritev).
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* The stack_t type no longer has the name struct sigaltstack. This changes
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the C++ name mangling for interfaces involving this type.
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* The ucontext_t type no longer has the name struct ucontext. This changes
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the C++ name mangling for interfaces involving this type.
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* On M68k GNU/Linux and MIPS GNU/Linux, the fpregset_t type no longer has
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the name struct fpregset. On Nios II GNU/Linux, the mcontext_t type no
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longer has the name struct mcontext. On SPARC GNU/Linux, the struct
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mc_fq, struct rwindow, struct fpq and struct fq types are no longer
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defined in sys/ucontext.h, the mc_fpu_t type no longer has the name struct
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mc_fpu, the gwindows_t type no longer has the name struct gwindows and the
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fpregset_t type no longer has the name struct fpu. This changes the C++
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name mangling for interfaces involving those types.
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* The synchronization that pthread_spin_unlock performs has been changed
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to now be equivalent to a C11 atomic store with release memory order to
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the spin lock's memory location. This ensures correct synchronization
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for the spin lock's operations and critical sections protected by a spin
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lock. Previously, several (but not all) architectures used stronger
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synchronization (e.g., containing what is often called a full barrier).
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This change can improve performance, but may affect odd fringe uses of
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spin locks that depend on the previous behavior (e.g., using spin locks
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as atomic variables to try to implement Dekker's mutual exclusion
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algorithm).
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* The tunables feature is now enabled by default. This allows users to tweak
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behavior of the GNU C Library using the GLIBC_TUNABLES environment variable.
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* The s390 specific ptrace requests are adjusted to the kernel ones. Request 12
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is now used for PTRACE_SINGLEBLOCK instead of PTRACE_GETREGS. The requests
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PTRACE_GETREGS, PTRACE_SETREGS, PTRACE_GETFPREGS and PTRACE_SETFPREGS were
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removed as those are not supported by the s390 kernel. The requests
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PTRACE_SINGLEBLOCK, PTRACE_SECCOMP_GET_FILTER, PTRACE_PEEKUSR_AREA,
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PTRACE_POKEUSR_AREA, PTRACE_GET_LAST_BREAK, PTRACE_ENABLE_TE,
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PTRACE_DISABLE_TE and PTRACE_TE_ABORT_RAND were added as those are supported
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by the s390 kernel.
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* The minimum GCC version that can be used to build this version of the GNU
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C Library is GCC 4.9. Older GCC versions, and non-GNU compilers, can
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still be used to compile programs using the GNU C Library.
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* The minimum GNU Binutils version that can be used to build this version of
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the GNU C Library is Binutils 2.25.
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* Support is added, on powerpc64le, x86_64, x86 and ia64, for interfaces
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supporting the _Float128 type from ISO/IEC TS 18661-3:2015. Most of the
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interfaces are taken from TS 18661-3. The type-generic macros in <math.h>
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and <tgmath.h> support this type. The GNU C Library now requires GCC 6.2
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or later to build for powerpc64le. When used with GCC versions before GCC
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7, these interfaces may be used with the type under the non-standard name
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__float128.
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To compile programs that use this feature, the compiler must support
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128-bit floating point with the type name _Float128 (as defined by
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TS 18661-3) or __float128 (the nonstandard name used by GCC prior to
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version 7).
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New <stdlib.h> functions from ISO/IEC TS 18661-3:
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@ -230,24 +152,111 @@ Version 2.26
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- Exponential and Logarithmic Function: clog10f128.
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* When the “rotate” (RES_ROTATE) DNS stub resolver option is active, glibc
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will now randomly pick a name server from the configuration as a starting
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point. (Previously, the second name server was always used.)
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Deprecated and removed features, and other changes affecting compatibility:
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* The synchronization that pthread_spin_unlock performs has been changed to
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now be equivalent to a C11 atomic store with release memory order to the
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spin lock's memory location. Previously, several (but not all)
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architectures used stronger synchronization (e.g., containing what is
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often called a full barrier). This change can improve performance, but
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may affect odd fringe uses of spin locks that depend on the previous
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behavior (e.g., using spin locks as atomic variables to try to implement
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Dekker's mutual exclusion algorithm).
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* The port to Native Client running on ARMv7-A (--host=arm-nacl) has been
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removed.
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* Sun RPC is deprecated. The rpcgen program, librpcsvc, and Sun RPC headers
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will only be built and installed when glibc is configured with
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--enable-obsolete-rpc. This allows alternative RPC implementations, such
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as TIRPC or rpcsvc-proto, to be used.
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* The NIS(+) name service modules, libnss_nis, libnss_nisplus, and
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libnss_compat, are deprecated, and will not be built or installed by
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default.
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The NIS(+) support library, libnsl, is also deprecated. By default, a
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compatibility shared library will be built and installed, but not headers
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or development libraries. Only a few NIS-related programs require this
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library. (In particular, glibc has never required programs that use
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'gethostbyname' to be linked with libnsl.)
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Replacement implementations based on TIRPC, which additionally support
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IPv6, are available from <https://github.com/thkukuk/>. The configure
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option --enable-obsolete-nsl will cause libnsl's headers, and the NIS(+)
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name service modules, to be built and installed.
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* The DNS stub resolver no longer performs EDNS fallback. If EDNS or DNSSEC
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support is enabled, the configured recursive resolver must support EDNS.
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(Responding to EDNS-enabled queries with responses which are not
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EDNS-enabled is fine, but FORMERR responses are not.)
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* res_mkquery and res_nmkquery no longer support the IQUERY opcode. DNS
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servers have not supported this opcode for a long time.
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* The _res_opcodes variable has been removed from libresolv. It had been
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exported by accident.
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* The glibc DNS stub resolver now supports an arbitary number of search
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domains (configured using the “search” directive in /etc/resolv.conf).
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Most applications will automatically benefit from this change, but for
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backwards compatibility reasons, applications which directly modify _res
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objects (which contain the resolver state, including the search list
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array, which is limited to six entries) will only use the first six search
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domains, as before.
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* <string.h> no longer includes inline versions of any string functions,
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as this kind of optimization is better done by the compiler. The macros
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__USE_STRING_INLINES and __NO_STRING_INLINES no longer have any effect.
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* The glibc DNS stub resolver now automatically reloads /etc/resolv.conf,
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to pick up changed configuration settings. The new “no-reload”
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(RES_NORELOAD) resolver option disables this behavior.
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* The nonstandard header <xlocale.h> has been removed. Most programs should
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use <locale.h> instead. If you have a specific need for the definition of
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locale_t with no other declarations, please contact
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libc-alpha@sourceware.org and explain.
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* The obsolete header <sys/ultrasound.h> has been removed.
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* The obsolete signal constant SIGUNUSED is no longer defined by <signal.h>.
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* The obsolete function cfree has been removed. Applications should use
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free instead.
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* The stack_t type no longer has the name struct sigaltstack. This changes
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the C++ name mangling for interfaces involving this type.
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* The ucontext_t type no longer has the name struct ucontext. This changes
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the C++ name mangling for interfaces involving this type.
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* On M68k GNU/Linux and MIPS GNU/Linux, the fpregset_t type no longer has
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the name struct fpregset. On Nios II GNU/Linux, the mcontext_t type no
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longer has the name struct mcontext. On SPARC GNU/Linux, the struct
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mc_fq, struct rwindow, struct fpq and struct fq types are no longer
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defined in sys/ucontext.h, the mc_fpu_t type no longer has the name struct
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mc_fpu, the gwindows_t type no longer has the name struct gwindows and the
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fpregset_t type no longer has the name struct fpu. This changes the C++
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name mangling for interfaces involving those types.
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* On S/390 GNU/Linux, the constants defined by <sys/ptrace.h> have been
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synced with the kernel:
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- PTRACE_GETREGS, PTRACE_SETREGS, PTRACE_GETFPREGS and PTRACE_SETFPREGS
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are not supported on this architecture and have been removed.
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- PTRACE_SINGLEBLOCK, PTRACE_SECCOMP_GET_FILTER, PTRACE_PEEKUSR_AREA,
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PTRACE_POKEUSR_AREA, PTRACE_GET_LAST_BREAK, PTRACE_ENABLE_TE,
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PTRACE_DISABLE_TE and PTRACE_TE_ABORT_RAND have been added.
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Programs that assume the GET/SETREGS ptrace requests are universally
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available will now fail to build, instead of malfunctioning at runtime.
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Changes to build and runtime requirements:
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* Linux kernel 3.2 or later is required at runtime, on all architectures
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supported by that kernel. (This is a change from version 2.25 only for
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x86-32 and x86-64.)
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* GNU Binutils 2.25 or later is now required to build glibc.
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* On most architectures, GCC 4.9 or later is required to build glibc. On
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powerpc64le, GCC 6.2 or later is required.
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Older GCC versions and non-GNU compilers are still supported when
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compiling programs that use glibc. (We do not know exactly how old,
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and some GNU extensions to C may be _de facto_ required. If you are
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interested in helping us make this statement less vague, please
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contact libc-alpha@sourceware.org.)
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Security related changes:
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