What's new:
-----------

- An IP-sampling profiler named 'profiler' has been added.  It can be used
  to profile any Cygwin program along with any DLLs loaded.

- A new tool 'gmondump' has been added.  It can dump the raw information
  of any "gmon.out" file created by profiler, ssp, or use of the gcc/g++
  option '-pg'.  (Continue using gprof to get symbolic profile displays.)

- New GNU-specific APIs, slated to become part of the next POSIX standard:
  pthread_cond_clockwait, pthread_mutex_clocklock, pthread_rwlock_clockrdlock,
  pthread_rwlock_clockwrlock, sem_clockwait.

- New Solaris-specific APIs, slated to become part of the next POSIX standard:
  sig2str, str2sig.


What changed:
-------------

- The speed argument to cfsetspeed(3) can now be a numerical baud rate
  rather than a Bnnn constant, as on Linux.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-July/248887.html

- The internal implementation of pipes has been overhauled; this
  should result in improved performance.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-August/249238.html


Bug Fixes
---------

- Fix values returned by select(2) for shutdown sockets.
  Addresses: https://cygwin.com/pipermail/cygwin-developers/2021-April/012092.html

- Introduce a new hypotl(3) function not suffering unnecessary overflows.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-April/248302.html

- Fix path handling for paths spanning native symlinks.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-April/248307.html

- Fix tab position evaluation after console window resize.

- Fix a regression in pseudo console handling, resulting in rlwrap not
  being able to start a new pseudo console.

- Handle two race conditions in pseudo console usage.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-April/248292.html

- Fix a bug in recognizing a successful completion of connect(2) on a
  datagram socket.

- Fix connect(2) when called with an address structure whose family is
  AF_UNSPEC.  As specified by POSIX and Linux, this is allowed on
  datagram sockets, and its effect is to reset the socket's peer
  address.

- Fix nanosleep(2) returning negative rem. NtQueryTimer appears to be able to
  return a negative remaining time (less than the timer resolution) for
  unsignalled timers.

- Fix getifaddrs(3) returning address family 0 or IPv4 address 0.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-July/248970.html

- Fix getaddrinfo(3) to return valid ai_socktype and ai_protocol values
  if the underlying GetAddrInfoW screws up.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-July/248985.html

- Fix duplicate /proc/partitions entries and (presumably) duplicate PIDs
  in ps(1) output.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-July/248998.html
             https://cygwin.com/pipermail/cygwin/2021-August/249124.html

- Fix pty master closing error regarding attach_mutex.
  Addresses: https://cygwin.com/pipermail/cygwin-developers/2021-October/012418.html

- Fix access violation that can sometimes occur when copy/pasting between
  32-bit and 64-bit Cygwin environments.  Align clipboard descriptor layouts.
  Addresses: https://cygwin.com/pipermail/cygwin-patches/2021q4/011517.html

- Fix a synchronization issue when running multiple threads from DLL
  initialization which in turn call malloc.
  Addresses: https://cygwin.com/pipermail/cygwin/2021-October/249635.html