GNU C Library NEWS -- history of user-visible changes.
Copyright (C) 1992-2019 Free Software Foundation, Inc.
See the end for copying conditions.

Please send GNU C library bug reports via <https://sourceware.org/bugzilla/>
using `glibc' in the "product" field.

Version 2.30

Major new features:

* Unicode 12.1.0 Support: Character encoding, character type info, and
  transliteration tables are all updated to Unicode 12.1.0, using
  generator scripts contributed by Mike FABIAN (Red Hat).

* The dynamic linker accepts the --preload argument to preload shared
  objects, in addition to the LD_PRELOAD environment variable.

* The twalk_r function has been added.  It is similar to the existing
  twalk function, but it passes an additional caller-supplied argument
  to the callback function.

* On Linux, the getdents64, gettid, and tgkill functions have been added.

* Minguo (Republic of China) calendar support has been added as an
  alternative calendar for the following locales: zh_TW, cmn_TW, hak_TW,
  nan_TW, lzh_TW.

* The entry for the new Japanese era has been added for ja_JP locale.

* Memory allocation functions malloc, calloc, realloc, reallocarray, valloc,
  pvalloc, memalign, and posix_memalign fail now with total object size
  larger than PTRDIFF_MAX.  This is to avoid potential undefined behavior with
  pointer subtraction within the allocated object, where results might
  overflow the ptrdiff_t type.

* The dynamic linker no longer refuses to load objects which reference
  versioned symbols whose implementation has moved to a different soname
  since the object has been linked.  The old error message, symbol
  FUNCTION-NAME, version SYMBOL-VERSION not defined in file DSO-NAME with
  link time reference, is gone.

* Add new POSIX-proposed pthread_cond_clockwait, pthread_mutex_clocklock,
  pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock and sem_clockwait
  functions.  These behave similarly to their "timed" equivalents, but also
  accept a clockid_t parameter to determine which clock their timeout should
  be measured against.  All functions allow waiting against CLOCK_MONOTONIC
  and CLOCK_REALTIME.  The decision of which clock to be used is made at the
  time of the wait (unlike with pthread_condattr_setclock, which requires
  the clock choice at initialization time).

* On AArch64 the GNU IFUNC resolver call ABI changed: old resolvers still
  work, new resolvers can use a second argument which can be extended in
  the future, currently it contains the AT_HWCAP2 value.

Deprecated and removed features, and other changes affecting compatibility:

* The copy_file_range function fails with ENOSYS if the kernel does not
  support the system call of the same name.  Previously, user space
  emulation was performed, but its behavior did not match the kernel
  behavior, which was deemed too confusing.  Applications which use the
  copy_file_range function can no longer rely on glibc to provide a fallback
  on kernels that do not support the copy_file_range system call, and if
  this function returns ENOSYS, they will need to use their own fallback.
  Support for copy_file_range for most architectures was added in version
  4.5 of the mainline Linux kernel.

* The functions clock_gettime, clock_getres, clock_settime,
  clock_getcpuclockid, clock_nanosleep were removed from the librt library
  for new applications (on architectures which had them).  Instead, the
  definitions in libc will be used automatically, which have been available
  since glibc 2.17.

* The obsolete and never-implemented XSI STREAMS header files <stropts.h>
  and <sys/stropts.h> have been removed.

* Support for the "inet6" option in /etc/resolv.conf and the RES_USE_INET6
  resolver flag (deprecated in glibc 2.25) have been removed.

* The obsolete RES_INSECURE1 and RES_INSECURE2 option flags for the DNS stub
  resolver have been removed from <resolv.h>.

* With --enable-bind-now, installed programs are now linked with the
  BIND_NOW flag.

* Support for the PowerPC SPE ISA extension (powerpc-*-*gnuspe*
  configurations) has been removed, following the deprecation of this
  subarchitecture in version 8 of GCC, and its removal in version 9.

* On 32-bit Arm, support for the port-based I/O emulation and the <sys/io.h>
  header have been removed.

* The Linux-specific <sys/sysctl.h> header and the sysctl function have been
  deprecated and will be removed from a future version of glibc.
  Application should directly access /proc instead.  For obtaining random
  bits, the getentropy function can be used.

Changes to build and runtime requirements:

* GCC 6.2 or later is required to build the GNU C Library.

  Older GCC versions and non-GNU compilers are still supported when
  compiling programs that use the GNU C Library.

Security related changes:

  CVE-2019-7309: x86-64 memcmp used signed Jcc instructions to check
  size.  For x86-64, memcmp on an object size larger than SSIZE_MAX
  has undefined behavior.  On x32, the size_t argument may be passed
  in the lower 32 bits of the 64-bit RDX register with non-zero upper
  32 bits.  When it happened with the sign bit of RDX register set,
  memcmp gave the wrong result since it treated the size argument as
  zero.  Reported by H.J. Lu.

  CVE-2019-9169: Attempted case-insensitive regular-expression match
  via proceed_next_node in posix/regexec.c leads to heap-based buffer
  over-read.  Reported by Hongxu Chen.

The following bugs are resolved with this release:

  [2872] locale: Transliteration Cyrillic -> ASCII fails
  [6399] libc: gettid() should have a wrapper
  [16573] malloc: mtrace hangs when MALLOC_TRACE is defined
  [16976] glob: fnmatch unbounded stack VLA for collating symbols
  [17396] localedata: globbing for locale by [[.collating-element.]]
  [18035] dynamic-link: pldd does no longer work, enters infinite loop
  [18465] malloc: memusagestat is built using system C library
  [18830] locale: iconv -c -f ascii with >buffer size worth of input before
    invalid input drops valid char
  [20188] nptl: libpthread IFUNC resolver for vfork can lead to crash
  [20568] locale: Segfault with wide characters and setlocale/fgetwc/UTF-8
  [21897] localedata: Afar locales: Fix mon, abmon, and abday
  [22964] localedata: The Japanese Era name will be changed on May 1, 2019
  [23352] malloc: __malloc_check_init still defined in public header
    malloc.h.
  [23403] nptl: Wrong alignment of TLS variables
  [23501] libc: nftw() doesn't return dangling symlink's inode
  [23733] malloc: Check the count before calling tcache_get()
  [23741] malloc: Missing __attribute_alloc_size__ in many allocation
    functions
  [23831] localedata: nl_NL missing LC_NUMERIC thousands_sep
  [23844] nptl: pthread_rwlock_trywrlock results in hang
  [23983] argparse: Missing compat versions of argp_failure and argp_error
    for long double = double
  [23984] libc: Missing compat versions of err.h and error.h functions for
    long double = double
  [23996] localedata: Dutch salutations
  [24040] libc: riscv64: unterminated call chain in __thread_start
  [24047] network: libresolv should use IP_RECVERR/IPV6_RECVERR to avoid
    long timeouts
  [24051] stdio: puts and putchar ouput to _IO_stdout instead of stdout
  [24059] nss: nss_files: get_next_alias calls fgets_unlocked without
    checking for NULL.
  [24114] regex: regexec buffer read overrun in "grep -i
    '\(\(\)*.\)*\(\)\(\)\1'"
  [24122] libc: Segfaults if 0 returned from la_version
  [24153] stdio: Some input functions do not react to stdin assignment
  [24155] string: x32 memcmp can treat positive length as 0 (if sign bit in
    RDX is set) (CVE-2019-7309)
  [24161] nptl: __run_fork_handlers self-deadlocks in malloc/tst-mallocfork2
  [24164] libc: Systemtap probes need to use "nr" constraint on 32-bit Arm,
    not the default "nor"
  [24166] dynamic-link: Dl_serinfo.dls_serpath[1] in dlfcn.h causes UBSAN
    false positives, change to modern flexible array
  [24180] nptl: pthread_mutex_trylock does not use the correct order of
    instructions while maintaining the robust mutex list due to missing
    compiler barriers.
  [24194] librt: Non-compatibility symbols for clock_gettime etc. cause
    unnecessary librt dependencies
  [24200] localedata: Revert first_weekday removal in en_IE locale
  [24211] nptl: Use-after-free in Systemtap probe in pthread_join
  [24215] nptl: pthread_timedjoin_np should be a cancellation point
  [24216] malloc: Check for large bin list corruption when inserting
    unsorted chunk
  [24228] stdio: old x86 applications that use legacy libio crash on exit
  [24231] dynamic-link: [sparc64] R_SPARC_H34 implementation falls through
    to R_SPARC_H44
  [24293] localedata: Missing Minguo calendar support for TW locales
  [24296] localedata: Orthographic mistakes in 'day' and 'abday' sections in
    tt_RU (Tatar) locale
  [24307] localedata: Update locale data to Unicode 12.0.0
  [24323] dynamic-link: dlopen should not be able open PIE objects
  [24335] build: "Obsolete types detected" with Linux 5.0 headers
  [24369] localedata: Orthographic mistakes in 'mon' and 'abmon' sections in
    tt_RU (Tatar) locale
  [24370] localedata: Add lang_name for tt_RU locale
  [24372] locale: Binary locale files are not architecture independent
  [24394] time: strptime %Ey mis-parses final year of era
  [24476] dynamic-link: __libc_freeres triggers bad free in libdl if dlerror
    was not used
  [24506] dynamic-link: FAIL: elf/tst-pldd with --enable-hardcoded-path-in-
    tests
  [24531] malloc: Malloc tunables give tcache assertion failures
  [24532] libc: conform/arpa/inet.h failures due to linux kernel 64-bit
    time_t changes
  [24535] localedata: Update locale data to Unicode 12.1.0
  [24537] build: nptl/tst-eintr1 test case can hit task limits on some
    kernels and break testing
  [24544] build: elf/tst-pldd doesn't work if you install with a --prefix
  [24556] build: [GCC 9] error: ‘%s’ directive argument is null
    [-Werror=format-overflow=]
  [24570] libc: alpha: compat msgctl uses __IPC_64
  [24584] locale: Data race in __wcsmbs_clone_conv
  [24588] stdio: Remove codecvt vtables from libio
  [24603] math: sysdeps/ieee754/dbl-64/branred.c is slow when compiled with
    -O3 -march=skylake
  [24614] localedata: nl_NL LC_MONETARY doesn't match CLDR 35
  [24632] stdio: Old binaries which use freopen with default stdio handles
    crash
  [24640] libc: __ppc_get_timebase_freq() always return 0 when using static
    linked glibc
  [24652] localedata: szl_PL spelling correction
  [24695] nss: nss_db: calling getpwent after endpwent crashes
  [24696] nss: endgrent() clobbers errno=ERRNO for 'group: db files' entry
    in /etc/nsswitch.conf
  [24699] libc: mmap64 with very large offset broken on MIPS64 n32
  [24740] libc: getdents64 type confusion
  [24741] dynamic-link: ld.so should not require that a versioned symbol is
    always implemented in the same library
  [24744] libc: Remove copy_file_range emulation
  [24757] malloc: memusagestat is linked against system libpthread
  [24794] libc: Partial test suite run builds corrupt test-in-container
    testroot


Version 2.29

Major new features:

* The getcpu wrapper function has been added, which returns the currently
  used CPU and NUMA node.  This function is Linux-specific.

* A new convenience target has been added for distribution maintainers
  to build and install all locales as directories with files.  The new
  target is run by issuing the following command in your build tree:
  'make localedata/install-locale-files', with an optional DESTDIR
  to set the install root if you wish to install into a non-default
  configured location.

* Optimized generic exp, exp2, log, log2, pow, sinf, cosf, sincosf and tanf.

* The reallocarray function is now declared under _DEFAULT_SOURCE, not just
  for _GNU_SOURCE, to match BSD environments.

* For powercp64le ABI, Transactional Lock Elision is now enabled iff kernel
  indicates that it will abort the transaction prior to entering the kernel
  (PPC_FEATURE2_HTM_NOSC on hwcap2).  On older kernels the transaction is
  suspended, and this caused some undefined side-effects issues by aborting
  transactions manually.  Glibc avoided it by abort transactions manually on
  each syscall, but it lead to performance issues on newer kernels where the
  HTM state is saved and restore lazily (the state being saved even when the
  process actually does not use HTM).

* The functions posix_spawn_file_actions_addchdir_np and
  posix_spawn_file_actions_addfchdir_np have been added, enabling
  posix_spawn and posix_spawnp to run the new process in a different
  directory.  These functions are GNU extensions.  The function
  posix_spawn_file_actions_addchdir_np is similar to the Solaris function
  of the same name.

* The popen and system do not run atfork handlers anymore (BZ#17490).
  Although it is a possible POSIX violation, the POSIX rationale in
  pthread_atfork documentation regarding atfork handlers is to handle
  inconsistent mutex state after a fork call in a multi-threaded process.
  In both popen and system there is no direct access to user-defined mutexes.

* Support for the C-SKY ABIV2 running on Linux has been added.  This port
  requires at least binutils-2.32, gcc-9.0, and linux-4.20.  Two ABIs are
  supported:
    - C-SKY ABIV2 soft-float little-endian
    - C-SKY ABIV2 hard-float little-endian

* strftime's default formatting of a locale's alternative year (%Ey)
  has been changed to zero-pad the year to a minimum of two digits,
  like "%y".  This improves the display of Japanese era years during
  the first nine years of a new era, and is expected to be harmless
  for all other locales (only Japanese locales regularly have
  alternative year numbers less than 10).  Zero-padding can be
  overridden with the '_' or '-' flags (which are GNU extensions).

* As a GNU extension, the '_' and '-' flags can now be applied to
  "%EY" to control how the year number is formatted; they have the
  same effect that they would on "%Ey".

Deprecated and removed features, and other changes affecting compatibility:

* The glibc.tune tunable namespace has been renamed to glibc.cpu and the
  tunable glibc.tune.cpu has been renamed to glibc.cpu.name.

* The type of the pr_uid and pr_gid members of struct elf_prpsinfo, defined
  in <sys/procfs.h>, has been corrected to match the type actually used by
  the Linux kernel.  This affects the size and layout of that structure on
  MicroBlaze, MIPS (n64 ABI only), Nios II and RISC-V.

* For the MIPS n32 ABI, the type of the pr_sigpend and pr_sighold members of
  struct elf_prstatus, and the pr_flag member of struct elf_prpsinfo,
  defined in <sys/procfs.h>, has been corrected to match the type actually
  used by the Linux kernel.  This affects the size and layout of those
  structures.

* An archaic GNU extension to scanf, under which '%as', '%aS', and '%a[...]'
  meant to scan a string and allocate space for it with malloc, is now
  restricted to programs compiled in C89 or C++98 mode with _GNU_SOURCE
  defined.  This extension conflicts with C99's use of '%a' to scan a
  hexadecimal floating-point number, which is now available to programs
  compiled as C99 or C++11 or higher, regardless of _GNU_SOURCE.

  POSIX.1-2008 includes the feature of allocating a buffer for string input
  with malloc, using the modifier letter 'm' instead.  Programs using
  '%as', '%aS', or '%a[...]' with the old GNU meaning should change to
  '%ms', '%mS', or '%m[...]' respectively.  Programs that wish to use the
  C99 '%a' no longer need to avoid _GNU_SOURCE.

  GCC's -Wformat warnings can detect most uses of this extension, as long
  as all functions that call vscanf, vfscanf, or vsscanf are annotated with
  __attribute__ ((format (scanf, ...))).

Changes to build and runtime requirements:

* Python 3.4 or later is required to build the GNU C Library.

* On most architectures, GCC 5 or later is required to build the GNU C
  Library.  (On powerpc64le, GCC 6.2 or later is still required, as before.)

  Older GCC versions and non-GNU compilers are still supported when
  compiling programs that use the GNU C Library.

Security related changes:

  CVE-2018-19591: A file descriptor leak in if_nametoindex can lead to a
  denial of service due to resource exhaustion when processing getaddrinfo
  calls with crafted host names.  Reported by Guido Vranken.

  CVE-2019-6488: On x32, the size_t parameter may be passed in the lower
  32 bits of a 64-bit register with with non-zero upper 32 bit.  When it
  happened, accessing the 32-bit size_t value as the full 64-bit register
  in the assembly string/memory functions would cause a buffer overflow.
  Reported by H.J. Lu.

  CVE-2016-10739: The getaddrinfo function could successfully parse IPv4
  addresses with arbitrary trailing characters, potentially leading to data
  or command injection issues in applications.

The following bugs are resolved with this release:

  [10425] localedata: it_IT/it_CH: LC_TIME format is wrong
  [10496] localedata: 12h time representation in multiple locales faulty
  [10797] localedata: it_IT locale numeric does not have a separator for
    thousands
  [11319] libc: dprintf doesn't handle errors properly
  [16346] time: mktime: potentially unsafe use of localtime_offset
  [17248] build: glibc should not sort CFLAGS (support gcc plugins and
    --param options)
  [17405] libc: Implement posix_spawn_file_actions_addchdir_np,
    posix_spawn_file_actions_addfchdir_np
  [17426] localedata: Indian locales: set the correct date format
  [17490] stdio: popen should not invoke atfork handlers
  [17783] libc: TIOCSER_TEMT conditions inconsistent
  [18040] regex: use-after-free in regexec/get_subexp
  [18093] libc: Corrupted aux-cache causes ldconfig to segfault
  [20018] network: getaddrinfo should reject IP addresses with trailing
    characters (CVE-2016-10739)
  [20209] localedata: Spelling mistake for Sunday in Greenlandic kl_GL
  [20271] libc: Missing "\n" in __libc_fatal calls
  [20480] dynamic-link: Patch: ifunc not executable, crashes sudo qemu
  [20544] libc: RFE: atexit, __cxa_atexit, on_exit should assert function
    pointer argument is non-NULL
  [21037] stdio: open_memstream and freopen
  [21286] libc: bits/siginfo.h  is missing enum definition for TRAP_HWBKPT
  [21716] time: Crash in glibc's mktime in low-memory situations
  [22834] stdio: Subprocess forked by popen may crash in Linux when
    multithreads call popen
  [22927] network: crash in vn_gai_enqueue_request if requests_tail was NULL
    and pthread_create fails.
  [23032] hurd: sysdeps/htl/pt-barrier-init.c:39: bad call to memcmp ?
  [23125] libc: riscv64: endless loop when throwing an exception from a
    constructor
  [23275] nptl: Race in pthread_mutex_lock while promoting to
    PTHREAD_MUTEX_ELISION_NP.
  [23400] libc: stdlib/test-bz22786.c creates temporary files in glibc
    source tree
  [23479] math: [mips] bits/fenv.h should not define some macros for soft-
    float
  [23490] libc: sysdeps/unix/sysv/linux/x86/tst-cet-property-2.c:49: off by
    one error
  [23497] libc: readdir64@GLIBC_2.1 cannot parse the kernel directory stream
  [23509] dynamic-link: CET enabled glibc is incompatible with the older
    linker
  [23520] nscd: nscd: Use-after-free in addgetnetgrentX and its callers
  [23521] nss: get_next_alias nss_files file stream leak
  [23538] nptl: Hang in pthread_cond_broadcast
  [23562] libc: Wrong type for si_band in Linux-specific siginfo_t
  [23578] regex: Invalid memory access if regex pattern contains NUL byte
  [23579] libc: Errors misreported in preadv2
  [23597] build: support/test-container.c doesn't work with different
    filesystems
  [23603] time: mktime signed integer overflow on large timestamps
  [23606] libc: Missing ENDBR32 in sysdeps/i386/start.S
  [23614] libc: powerpc: missing CFI register information in __mpn_*
    functions
  [23637] string: Generic strstr/strcasestr fails with huge needles
  [23640] libc: no way to easily clear FD_CLOEXEC in
    posix_spawn_file_actions_adddup2()
  [23649] libc: [microblaze/mips/nios2/riscv] sys/procfs.h pr_uid, pr_gid
    have wrong type
  [23656] libc: [mips n32] sys/procfs.h pr_sigpend, pr_sighold, pr_flag have
    wrong type
  [23679] libc: gethostid: Missing NULL check for gethostbyname_r result
  [23689] libc: Bug in documentation for rusage.ru_ixrss in
    bits/types/struct_rusage.h
  [23690] dynamic-link: Segfault in _dl_profile_fixup with a high number of
    threads
  [23707] dynamic-link: Missing unwind info in sysdeps/powerpc/powerpc32/dl-
    start.S
  [23709] string: glibc 2.25 lacks sse2 optimized strstr()
  [23716] dynamic-link: _dl_runtime_resolve_shstk isn't selected properly
  [23717] libc: glibc: stdlib/tst-setcontext9 test suite failure on
    powerpc64le
  [23724] localedata: Albanian date formats are incorrect
  [23735] math: libnldbl_nonshared.a references internal libm symbols
  [23740] localedata: kl_GL: Month names and date formats need update
  [23744] regex: regex refactorings to remove BE, avoid duplication
  [23745] time: mktime fix for Gnulib + coreutils
  [23758] time: Improve the width of alternate representation for year in
    strftime
  [23783] libc: [mips] Missing CMSPAR bits/termios.h
  [23789] time: mktime does not set errno on failure
  [23791] localedata: Wrong monetary format for ca_ES locale
  [23793] locale: c32rtomb and mbrtoc32 should not alias wcrtomb and mbrtowc
  [23794] locale: c16rtomb does not handle surrogate pairs
  [23821] libc: si_band in siginfo_t has wrong type long int on sparc64
  [23822] math: ia64 static libm.a is missing exp2f, log2f and powf symbols
  [23836] time: time/tst-mktime2 test failure on Arm (32-bit)
  [23848] libc: [sparc] Some socket syscalls wrongly assumed to be present
  [23861] nptl: rdlock stalls indefinitely on an unlocked pthread rwlock
  [23862] libc: [sh] missing kernel-features.h undefines
  [23864] libc: [riscv] missing kernel-features.h undefines
  [23867] libc: [arm/microblaze] __ASSUME_MLOCK2 incorrect
  [23907] malloc: Incorrect double-free malloc tcache check disregards
    tcache size
  [23913] libc: off-by-one in function maybe_script_execute in
    sysdeps/posix/spawni.c
  [23915] libc: [arm] __ASSUME_COPY_FILE_RANGE incorrect
  [23923] locale: Add --no-hard-links option to localedef
  [23927] network: Linux if_nametoindex() does not close descriptor
    (CVE-2018-19591)
  [23961] math: powf can overflow to inf without setting errno in non-
    nearest rounding mode
  [23967] libc: [2.28 Regression]: New sigaction implementation breaks m68k
  [23972] libc: __old_getdents64 uses wrong d_off value on overflow
  [23993] libc: glibc 2.29 doesn't build with gcc 4.9
  [23995] localedata: Remove execution flags from localedata/locales/bi_VU
  [24011] localedata: Fixed small type in comment for locale bs_BA
  [24018] libc: gettext() may return NULL
  [24022] build: riscv build failure with Linux kernel 4.20-rc7
  [24023] build: [2.29 Regression] FAIL: elf/check-localplt
  [24024] string: strerror() might set errno to ENOMEM due to -fno-math-
    error
  [24027] malloc: glibc: realloc() ncopies 32-bit integer overflow
  [24034] libc: tst-cancel21-static fails with SIGBUS on pre-ARMv7 when
    using GCC 8
  [24046] localedata: en_US locale doesn't define date_fmt
  [24063] manual: @var{errno} should be @code{errno}
  [24066] soft-fp: Inconsistent _FP_W_TYPE_SIZE check
  [24088] libc: VSCR field is not being correctly read in ucontext_t on
    ppc64le
  [24096] time: Specifying '_' or '-' flag for "%EY" does not produce the
    expected result
  [24097] string: Can't use 64-bit register for size_t in assembly codes for
    x32 (CVE-2019-6488)
  [24110] hurd: SS_DISABLE never set in stack_t value returned by
    sigaltstack
  [24112] network: Do not send DNS queries for non-host names (where all
    answers will be rejected)
  [24130] libc: alpha __remqu corrupts $f3 register


Version 2.28

Major new features:

* The localization data for ISO 14651 is updated to match the 2016
  Edition 4 release of the standard, this matches data provided by
  Unicode 9.0.0.  This update introduces significant improvements to the
  collation of Unicode characters.  This release deviates slightly from
  the standard in that the collation element ordering for lowercase and
  uppercase LATIN script characters is adjusted to ensure that regular
  expressions with ranges like [a-z] and [A-Z] don't interleave e.g. A
  is not matched by [a-z].  With the update many locales have been
  updated to take advantage of the new collation information.  The new
  collation information has increased the size of the compiled locale
  archive or binary locales.

* The GNU C Library can now be compiled with support for Intel CET, AKA
  Intel Control-flow Enforcement Technology.  When the library is built
  with --enable-cet, the resulting glibc is protected with indirect
  branch tracking (IBT) and shadow stack (SHSTK).  CET-enabled glibc 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 CET-enabled glibc requires CPUs
  capable of multi-byte NOPs, like x86-64 processors as well as Intel
  Pentium Pro or newer.  NOTE: --enable-cet has been tested for i686,
  x86_64 and x32 on non-CET processors.  --enable-cet has been tested
  for x86_64 and x32 on CET SDVs, but Intel CET support hasn't been
  validated for i686.

* The GNU C Library now has correct support for ABSOLUTE symbols
  (SHN_ABS-relative symbols).  Previously such ABSOLUTE symbols were
  relocated incorrectly or in some cases discarded.  The GNU linker can
  make use of the newer semantics, but it must communicate it to the
  dynamic loader by setting the ELF file's identification (EI_ABIVERSION
  field) to indicate such support is required.

* Unicode 11.0.0 Support: Character encoding, character type info, and
  transliteration tables are all updated to Unicode 11.0.0, using
  generator scripts contributed by Mike FABIAN (Red Hat).

* <math.h> functions that round their results to a narrower type are added
  from TS 18661-1:2014 and TS 18661-3:2015:

  - fadd, faddl, daddl and corresponding fMaddfN, fMaddfNx, fMxaddfN and
    fMxaddfNx functions.

  - fsub, fsubl, dsubl and corresponding fMsubfN, fMsubfNx, fMxsubfN and
    fMxsubfNx functions.

  - fmul, fmull, dmull and corresponding fMmulfN, fMmulfNx, fMxmulfN and
    fMxmulfNx functions.

  - fdiv, fdivl, ddivl and corresponding fMdivfN, fMdivfNx, fMxdivfN and
    fMxdivfNx functions.

* Two grammatical forms of month names are now supported for the following
  languages: Armenian, Asturian, Catalan, Czech, Kashubian, Occitan, Ossetian,
  Scottish Gaelic, Upper Sorbian, and Walloon.  The following languages now
  support two grammatical forms in abbreviated month names: Catalan, Greek,
  and Kashubian.

* Newly added locales: Lower Sorbian (dsb_DE) and Yakut (sah_RU) also
  include the support for two grammatical forms of month names.

* Building and running on GNU/Hurd systems now works without out-of-tree
  patches.

* The renameat2 function has been added, a variant of the renameat function
  which has a flags argument.  If the flags are zero, the renameat2 function
  acts like renameat.  If the flag is not zero and there is no kernel
  support for renameat2, the function will fail with an errno value of
  EINVAL.  This is different from the existing gnulib function renameatu,
  which performs a plain rename operation in case of a RENAME_NOREPLACE
  flags and a non-existing destination (and therefore has a race condition
  that can clobber the destination inadvertently).

* The statx function has been added, a variant of the fstatat64
  function with an additional flags argument.  If there is no direct
  kernel support for statx, glibc provides basic stat support based on
  the fstatat64 function.

* IDN domain names in getaddrinfo and getnameinfo now use the system libidn2
  library if installed.  libidn2 version 2.0.5 or later is recommended.  If
  libidn2 is not available, internationalized domain names are not encoded
  or decoded even if the AI_IDN or NI_IDN flags are passed to getaddrinfo or
  getnameinfo.  (getaddrinfo calls with non-ASCII names and AI_IDN will fail
  with an encoding error.)  Flags which used to change the IDN encoding and
  decoding behavior (AI_IDN_ALLOW_UNASSIGNED, AI_IDN_USE_STD3_ASCII_RULES,
  NI_IDN_ALLOW_UNASSIGNED, NI_IDN_USE_STD3_ASCII_RULES) have been
  deprecated.  They no longer have any effect.

* Parsing of dynamic string tokens in DT_RPATH, DT_RUNPATH, DT_NEEDED,
  DT_AUXILIARY, and DT_FILTER has been expanded to support the full
  range of ELF gABI expressions including such constructs as
  '$ORIGIN$ORIGIN' (if valid).  For SUID/GUID applications the rules
  have been further restricted, and where in the past a dynamic string
  token sequence may have been interpreted as a literal string it will
  now cause a load failure.  These load failures were always considered
  unspecified behaviour from the perspective of the dynamic loader, and
  for safety are now load errors e.g. /foo/${ORIGIN}.so in DT_NEEDED
  results in a load failure now.

* Support for ISO C threads (ISO/IEC 9899:2011) has been added.  The
  implementation includes all the standard functions provided by
  <threads.h>:

  - thrd_current, thrd_equal, thrd_sleep, thrd_yield, thrd_create,
    thrd_detach, thrd_exit, and thrd_join for thread management.

  - mtx_init, mtx_lock, mtx_timedlock, mtx_trylock, mtx_unlock, and
    mtx_destroy for mutual exclusion.

  - call_once for function call synchronization.

  - cnd_broadcast, cnd_destroy, cnd_init, cnd_signal, cnd_timedwait, and
    cnd_wait for conditional variables.

  - tss_create, tss_delete, tss_get, and tss_set for thread-local storage.

  Application developers must link against libpthread to use ISO C threads.

Deprecated and removed features, and other changes affecting compatibility:

* The nonstandard header files <libio.h> and <_G_config.h> are no longer
  installed.  Software that was using either header should be updated to
  use standard <stdio.h> interfaces instead.

* The stdio functions 'getc' and 'putc' are no longer defined as macros.
  This was never required by the C standard, and the macros just expanded
  to call alternative names for the same functions.  If you hoped getc and
  putc would provide performance improvements over fgetc and fputc, instead
  investigate using (f)getc_unlocked and (f)putc_unlocked, and, if
  necessary, flockfile and funlockfile.

* All stdio functions now treat end-of-file as a sticky condition.  If you
  read from a file until EOF, and then the file is enlarged by another
  process, you must call clearerr or another function with the same effect
  (e.g. fseek, rewind) before you can read the additional data.  This
  corrects a longstanding C99 conformance bug.  It is most likely to affect
  programs that use stdio to read interactive input from a terminal.
  (Bug #1190.)

* The macros 'major', 'minor', and 'makedev' are now only available from
  the header <sys/sysmacros.h>; not from <sys/types.h> or various other
  headers that happen to include <sys/types.h>.  These macros are rarely
  used, not part of POSIX nor XSI, and their names frequently collide with
  user code; see https://sourceware.org/bugzilla/show_bug.cgi?id=19239 for
  further explanation.

  <sys/sysmacros.h> is a GNU extension.  Portable programs that require
  these macros should first include <sys/types.h>, and then include
  <sys/sysmacros.h> if __GNU_LIBRARY__ is defined.

* The tilegx*-*-linux-gnu configurations are no longer supported.

* The obsolete function ustat is no longer available to newly linked
  binaries; the headers <ustat.h> and <sys/ustat.h> have been removed.  This
  function has been deprecated in favor of fstatfs and statfs.

* The obsolete function nfsservctl is no longer available to newly linked
  binaries.  This function was specific to systems using the Linux kernel
  and could not usefully be used with the GNU C Library on systems with
  version 3.1 or later of the Linux kernel.

* The obsolete function name llseek is no longer available to newly linked
  binaries.  This function was specific to systems using the Linux kernel
  and was not declared in a header.  Programs should use the lseek64 name
  for this function instead.

* The AI_IDN_ALLOW_UNASSIGNED and NI_IDN_ALLOW_UNASSIGNED flags for the
  getaddrinfo and getnameinfo functions have been deprecated.  The behavior
  previously selected by them is now always enabled.

* The AI_IDN_USE_STD3_ASCII_RULES and NI_IDN_USE_STD3_ASCII_RULES flags for
  the getaddrinfo and getnameinfo functions have been deprecated.  The STD3
  restriction (rejecting '_' in host names, among other things) has been
  removed, for increased compatibility with non-IDN name resolution.

* The fcntl function now have a Long File Support variant named fcntl64.  It
  is added to fix some Linux Open File Description (OFD) locks usage on non
  LFS mode.  As for others *64 functions, fcntl64 semantics are analogous with
  fcntl and LFS support is handled transparently.  Also for Linux, the OFD
  locks act as a cancellation entrypoint.

* The obsolete functions encrypt, encrypt_r, setkey, setkey_r, cbc_crypt,
  ecb_crypt, and des_setparity are no longer available to newly linked
  binaries, and the headers <rpc/des_crypt.h> and <rpc/rpc_des.h> are no
  longer installed.  These functions encrypted and decrypted data with the
  DES block cipher, which is no longer considered secure.  Software that
  still uses these functions should switch to a modern cryptography library,
  such as libgcrypt.

* Reflecting the removal of the encrypt and setkey functions above, the
  macro _XOPEN_CRYPT is no longer defined.  As a consequence, the crypt
  function is no longer declared unless _DEFAULT_SOURCE or _GNU_SOURCE is
  enabled.

* The obsolete function fcrypt is no longer available to newly linked
  binaries.  It was just another name for the standard function crypt,
  and it has not appeared in any header file in many years.

* We have tentative plans to hand off maintenance of the passphrase-hashing
  library, libcrypt, to a separate development project that will, we hope,
  keep up better with new passphrase-hashing algorithms.  We will continue
  to declare 'crypt' in <unistd.h>, and programs that use 'crypt' or
  'crypt_r' should not need to change at all; however, distributions will
  need to install <crypt.h> and libcrypt from a separate project.

  In this release, if the configure option --disable-crypt is used, glibc
  will not install <crypt.h> or libcrypt, making room for the separate
  project's versions of these files.  The plan is to make this the default
  behavior in a future release.

Changes to build and runtime requirements:

  GNU make 4.0 or later is now required to build glibc.

Security related changes:

  CVE-2016-6261, CVE-2016-6263, CVE-2017-14062: Various vulnerabilities have
  been fixed by removing the glibc-internal IDNA implementation and using
  the system-provided libidn2 library instead.  Originally reported by Hanno
  Böck and Christian Weisgerber.

  CVE-2017-18269: An SSE2-based memmove implementation for the i386
  architecture could corrupt memory.  Reported by Max Horn.

  CVE-2018-11236: Very long pathname arguments to realpath function could
  result in an integer overflow and buffer overflow.  Reported by Alexey
  Izbyshev.

  CVE-2018-11237: The mempcpy implementation for the Intel Xeon Phi
  architecture could write beyond the target buffer, resulting in a buffer
  overflow.  Reported by Andreas Schwab.

The following bugs are resolved with this release:

  [1190] stdio: fgetc()/fread() behaviour is not POSIX compliant
  [6889] manual: 'PWD' mentioned but not specified
  [13575] libc: SSIZE_MAX defined as LONG_MAX is inconsistent with ssize_t,
    when __WORDSIZE != 64
  [13762] regex: re_search etc. should return -2 on memory exhaustion
  [13888] build: /tmp usage during testing
  [13932] math: dbl-64 pow unexpectedly slow for some inputs
  [14092] nptl: Support C11 threads
  [14095] localedata: Review / update collation data from Unicode / ISO
    14651
  [14508] libc: -Wformat warnings
  [14553] libc: Namespace pollution loff_t in sys/types.h
  [14890] libc: Make NT_PRFPREG canonical.
  [15105] libc: Extra PLT references with -Os
  [15512] libc: __bswap_constant_16 not compiled when -Werror -Wsign-
    conversion is given
  [16335] manual: Feature test macro documentation incomplete and out of
    date
  [16552] libc: Unify umount implementations in terms of umount2
  [17082] libc: htons et al.: statement-expressions prevent use on global
    scope with -O1 and higher
  [17343] libc: Signed integer overflow in /stdlib/random_r.c
  [17438] localedata: pt_BR: wrong d_fmt delimiter
  [17662] libc: please implement binding for the new renameat2 syscall
  [17721] libc: __restrict defined as /* Ignore */ even in c11
  [17979] libc: inconsistency between uchar.h and stdint.h
  [18018] dynamic-link: Additional $ORIGIN handling issues (CVE-2011-0536)
  [18023] libc: extend_alloca is broken (questionable pointer comparison,
    horrible machine code)
  [18124] libc: hppa: setcontext erroneously returns -1 as exit code for
    last constant.
  [18471] libc: llseek should be a compat symbol
  [18473] soft-fp: [powerpc-nofpu] __sqrtsf2, __sqrtdf2 should be compat
    symbols
  [18991] nss: nss_files skips large entry in database
  [19239] libc: Including stdlib.h ends up with macros major and minor being
    defined
  [19463] libc: linknamespace failures when compiled with -Os
  [19485] localedata: csb_PL: Update month translations + add yesstr/nostr
  [19527] locale: Normalized charset name not recognized by setlocale
  [19667] string: Missing Sanity Check for malloc calls in file 'testcopy.c'
  [19668] libc: Missing Sanity Check for malloc() in file 'tst-setcontext-
    fpscr.c'
  [19728] network: out of bounds stack read in libidn function
    idna_to_ascii_4i (CVE-2016-6261)
  [19729] network: out of bounds heap read on invalid utf-8 inputs in
    stringprep_utf8_nfkc_normalize (CVE-2016-6263)
  [19818] dynamic-link: Absolute (SHN_ABS) symbols incorrectly relocated by
    the base address
  [20079] libc: Add SHT_X86_64_UNWIND to elf.h
  [20251] libc: 32bit programs pass garbage in struct flock for OFD locks
  [20419] dynamic-link: files with large allocated notes crash in
    open_verify
  [20530] libc: bswap_16 should use __builtin_bswap16() when available
  [20890] dynamic-link: ldconfig: fsync the files before atomic rename
  [20980] manual: CFLAGS environment variable replaces vital options
  [21163] regex: Assertion failure in pop_fail_stack when executing a
    malformed regexp (CVE-2015-8985)
  [21234] manual: use of CFLAGS makes glibc detect no optimization
  [21269] dynamic-link: i386 sigaction sa_restorer handling is wrong
  [21313] build: Compile Error GCC 5.4.0 MIPS with -0S
  [21314] build: Compile Error GCC 5.2.0 MIPS with -0s
  [21508] locale: intl/tst-gettext failure with latest msgfmt
  [21547] localedata: Tibetan script collation broken (Dzongkha and Tibetan)
  [21812] network: getifaddrs() returns entries with ifa_name == NULL
  [21895] libc: ppc64 setjmp/longjmp not fully interoperable with static
    dlopen
  [21942] dynamic-link: _dl_dst_substitute incorrectly handles $ORIGIN: with
    AT_SECURE=1
  [22241] localedata: New locale: Yakut (Sakha) locale for Russia (sah_RU)
  [22247] network: Integer overflow in the decode_digit function in
    puny_decode.c in libidn (CVE-2017-14062)
  [22342] nscd: NSCD not properly caching netgroup
  [22391] nptl: Signal function clear NPTL internal symbols inconsistently
  [22550] localedata: es_ES locale (and  other es_* locales):  collation
    should treat ñ  as a primary different character,  sync the collation
    for Spanish with CLDR
  [22638] dynamic-link: sparc: static binaries are broken if glibc is built
    by gcc configured with --enable-default-pie
  [22639] time: year 2039 bug for localtime etc. on 64-bit platforms
  [22644] string: memmove-sse2-unaligned on 32bit x86 produces garbage when
    crossing 2GB threshold (CVE-2017-18269)
  [22646] localedata: redundant data (LC_TIME) for es_CL, es_CU, es_EC and
    es_BO
  [22735] time: Misleading typo in time.h source comment regarding
    CLOCKS_PER_SECOND
  [22753] libc: preadv2/pwritev2 fallback code should handle offset=-1
  [22761] libc: No trailing `%n' conversion specifier in FMT passed from
    `__assert_perror_fail ()' to `__assert_fail_base ()'
  [22766] libc: all glibc internal dlopen should use RTLD_NOW for robust
    dlopen failures
  [22786] libc: Stack buffer overflow in realpath() if input size is close
    to SSIZE_MAX (CVE-2018-11236)
  [22787] dynamic-link: _dl_check_caller returns false when libc is linked
    through an absolute DT_NEEDED path
  [22792] build: tcb-offsets.h dependency dropped
  [22797] libc: pkey_get() uses non-reserved name of argument
  [22807] libc: PTRACE_* constants missing for powerpc
  [22818] glob: posix/tst-glob_lstat_compat failure on alpha
  [22827] dynamic-link: RISC-V ELF64 parser mis-reads flag in ldconfig
  [22830] malloc: malloc_stats doesn't restore cancellation state on stderr
  [22848] localedata: ca_ES: update date definitions from CLDR
  [22862] build: _DEFAULT_SOURCE is defined even when _ISOC11_SOURCE is
  [22884] math: RISCV fmax/fmin handle signalling NANs incorrectly
  [22896] localedata: Update locale data for an_ES
  [22902] math: float128 test failures with GCC 8
  [22918] libc: multiple common of `__nss_shadow_database'
  [22919] libc: sparc32: backtrace yields infinite backtrace with
    makecontext
  [22926] libc: FTBFS on powerpcspe
  [22932] localedata: lt_LT: Update of abbreviated month names from CLDR
    required
  [22937] localedata: Greek (el_GR, el_CY) locales actually need ab_alt_mon
  [22947] libc: FAIL: misc/tst-preadvwritev2
  [22963] localedata: cs_CZ: Add alternative month names
  [22987] math: [powerpc/sparc] fdim inlines errno, exceptions handling
  [22996] localedata: change LC_PAPER to en_US in es_BO locale
  [22998] dynamic-link: execstack tests are disabled when SELinux is
    disabled
  [23005] network: Crash in __res_context_send after memory allocation
    failure
  [23007] math: strtod cannot handle -nan
  [23024] nss: getlogin_r is performing NSS lookups when loginid isn't set
  [23036] regex: regex equivalence class regression
  [23037] libc: initialize msg_flags to zero for sendmmsg() calls
  [23069] libc: sigaction broken on riscv64-linux-gnu
  [23094] localedata: hr_HR: wrong thousands_sep and mon_thousands_sep
  [23102] dynamic-link: Incorrect parsing of multiple consecutive $variable
    patterns in runpath entries (e.g. $ORIGIN$ORIGIN)
  [23137] nptl: s390: pthread_join sometimes block indefinitely (on 31bit
    and libc build with -Os)
  [23140] localedata: More languages need two forms of month names
  [23145] libc: _init/_fini aren't marked as hidden
  [23152] localedata: gd_GB: Fix typo in "May" (abbreviated)
  [23171] math: C++ iseqsig for long double converts arguments to double
  [23178] nscd: sudo will fail when it is run in concurrent with commands
    that changes /etc/passwd
  [23196] string: __mempcpy_avx512_no_vzeroupper mishandles large copies
    (CVE-2018-11237)
  [23206] dynamic-link: static-pie + dlopen breaks debugger interaction
  [23208] localedata: New locale - Lower Sorbian (dsb)
  [23233] regex: Memory leak in build_charclass_op function in file
    posix/regcomp.c
  [23236] stdio: Harden function pointers in _IO_str_fields
  [23250] nptl: Offset of __private_ss differs from GCC
  [23253] math: tgamma test suite failures on i686 with -march=x86-64
    -mtune=generic -mfpmath=sse
  [23259] dynamic-link: Unsubstituted ${ORIGIN} remains in DT_NEEDED for
    AT_SECURE
  [23264] libc: posix_spawnp wrongly executes ENOEXEC in non compat mode
  [23266] nis: stringop-truncation warning with new gcc8.1 in nisplus-
    parser.c
  [23272] math: fma(INFINITY,INFIITY,0.0) should be INFINITY
  [23277] math: nan function should not have const attribute
  [23279] math: scanf and strtod wrong for some hex floating-point
  [23280] math: wscanf rounds wrong; wcstod is ok for negative numbers and
    directed rounding
  [23290] localedata: IBM273 is not equivalent to ISO-8859-1
  [23303] build: undefined reference to symbol
    '__parse_hwcap_and_convert_at_platform@@GLIBC_2.23'
  [23307] dynamic-link: Absolute symbols whose value is zero ignored in
    lookup
  [23313] stdio: libio vtables validation and standard file object
    interposition
  [23329] libc: The __libc_freeres infrastructure is not properly run across
    DSO boundaries.
  [23349] libc: Various glibc headers no longer compatible with
    <linux/time.h>
  [23351] malloc: Remove unused code related to heap dumps and malloc
    checking
  [23363] stdio: stdio-common/tst-printf.c has non-free license
  [23396] regex: Regex equivalence regression in single-byte locales
  [23422] localedata: oc_FR: More updates of locale data
  [23442] build: New warning with GCC 8
  [23448] libc: Out of bounds access in IBM-1390 converter
  [23456] libc: Wrong index_cpu_LZCNT
  [23458] build: tst-get-cpu-features-static isn't added to tests
  [23459] libc: COMMON_CPUID_INDEX_80000001 isn't populated for Intel
    processors
  [23467] dynamic-link: x86/CET: A property note parser bug


Version 2.27

Major new features:

* The GNU C Library can now be compiled with support for building static
  PIE executables (See --enable-static-pie in INSTALL).  These static PIE
  executables are like static executables but can be loaded at any address
  and provide additional security hardening benefits at the cost of some
  memory and performance.  When the library is built with --enable-static-pie
  the resulting libc.a is usable with GCC 8 and above to create static PIE
  executables using the GCC option '-static-pie'.  This feature is currently
  supported on i386, x86_64 and x32 with binutils 2.29 or later, and on
  aarch64 with binutils 2.30 or later.

* Optimized x86-64 asin, atan2, exp, expf, log, pow, atan, sin, cosf,
  sinf, sincosf and tan with FMA, contributed by Arjan van de Ven and
  H.J. Lu from Intel.

* Optimized x86-64 trunc and truncf for processors with SSE4.1.

* Optimized generic expf, exp2f, logf, log2f, powf, sinf, cosf and sincosf.

* In order to support faster and safer process termination the malloc API
  family of functions will no longer print a failure address and stack
  backtrace after detecting heap corruption.  The goal is to minimize the
  amount of work done after corruption is detected and to avoid potential
  security issues in continued process execution.  Reducing shutdown time
  leads to lower overall process restart latency, so there is benefit both
  from a security and performance perspective.

* The abort function terminates the process immediately, without flushing
  stdio streams.  Previous glibc versions used to flush streams, resulting
  in deadlocks and further data corruption.  This change also affects
  process aborts as the result of assertion failures.

* On platforms where long double has the IEEE binary128 format (aarch64,
  alpha, mips64, riscv, s390 and sparc), the math library now implements
  _Float128 interfaces for that type, as defined by ISO/IEC TS 18661-3:2015.
  These are the same interfaces added in version 2.26 for some platforms where
  this format is supported but is not the format of long double.

* On platforms with support for _Float64x (aarch64, alpha, i386, ia64,
  mips64, powerpc64le, riscv, s390, sparc and x86_64), the math library now
  implements interfaces for that type, as defined by ISO/IEC TS
  18661-3:2015.  These are corresponding interfaces to those supported for
  _Float128.

* The math library now implements interfaces for the _Float32, _Float64 and
  _Float32x types, as defined by ISO/IEC TS 18661-3:2015.  These are
  corresponding interfaces to those supported for _Float128.

* glibc now implements the memfd_create and mlock2 functions on Linux.

* Support for memory protection keys was added.  The <sys/mman.h> header now
  declares the functions pkey_alloc, pkey_free, pkey_mprotect, pkey_set,
  pkey_get.

* The copy_file_range function was added.

* Optimized memcpy, mempcpy, memmove, and memset for sparc M7.

* The ldconfig utility now processes `include' directives using the C/POSIX
  collation ordering.  Previous glibc versions used locale-specific
  ordering, the change might break systems that relied on that.

* Support for two grammatical forms of month names has been added.
  In a call to strftime, the "%B" and "%b" format specifiers will now
  produce the grammatical form required when the month is used as part
  of a complete date.  New "%OB" and "%Ob" specifiers produce the form
  required when the month is named by itself.  For instance, in Greek
  and in many Slavic and Baltic languages, "%B" will produce the month
  in genitive case, and "%OB" will produce the month in nominative case.

  In a call to strptime, "%B", "%b", "%h", "%OB", "%Ob", and "%Oh"
  are all valid and will all accept any known form of month
  name---standalone or complete, abbreviated or full.  In a call to
  nl_langinfo, the query constants MON_1..12 and ABMON_1..12 return
  the strings used by "%B" and "%b", respectively.  New query
  constants ALTMON_1..12 and _NL_ABALTMON_1..12 return the strings
  used by "%OB" and "%Ob", respectively.

  In a locale definition file, use "alt_mon" and "ab_alt_mon" to
  define the strings for %OB and %Ob, respectively; these have the
  same syntax as "mon" and "abmon".  These arrays are optional; if they
  are not provided then they have the same content as "mon" and "abmon",
  respectively.

  These features are provided for locales which define "alt_mon" and/or
  "ab_alt_mon" in their locale source data.  This release includes such
  alternative month name data for the following languages: Belarusian,
  Croatian, Greek, Lithuanian, Polish, Russian, and Ukrainian.

  This feature is currently a GNU extension, but it is expected to
  be added to the next revision of POSIX, and it is also already
  available on some BSD-derived operating systems.

  This feature will cause existing statically compiled applications
  to fail to load locales and fall back to the builtin C/POSIX locales.
  See notes below for other changes affecting compatibility.

* Support for the RISC-V ISA running on Linux has been added.  This port
  requires at least binutils-2.30, gcc-7.3.0, and linux-4.15; and is supported
  for the following ISA and ABI pairs:

